I don't object to A's annoyance over the material, nor to her removing and disposing of the pamphlets. As a library employee she's entitled and probably expected to do so. I did object to her use of the term "littering" (which in later comments she confirmed that she meant) and her complaint about those who "decide to preach to those who perhaps do not want to hear it".
"Litter" is certainly the wrong word. I like Wikipedia's definition:
Litter consists of waste products that have been disposed [of] improperly, without consent, in an inappropriate location. Litter can also be used as a verb. To litter means to throw (often man-made) objects onto the ground and leave them as opposed to disposing of them properly.
But Merriam-Webster's definition 4a will do as well: "trash, wastepaper, or garbage lying scattered about."
Those religious tracts were not dropped carelessly in the library stacks instead of being "disposed of properly." They weren't even "scattered about." Someone left them there deliberately and probably placed them with some care. Whatever one thinks of their contents, and I'd probably agree with my friend about that, they aren't litter. A was using the word to express her dislike for their content: compare this article from the Bloomington newspaper, which shows people using the same word about matter that was also placed deliberately and carefully.
As the discussion proceeded, some commenters argued that the library has the right to decide what is on its shelves. One declared that a library "is a fragile ecosystem and should be treated as such." This is difficult, though I think the "fragile ecosystem" claim is patent bullshit: libraries are tougher than that. My initial response was that I'd like to put atheist tracts in the hymnal racks of churches -- but no church may be responsible for the tracts A found; they may have been distributed by a free-lancer, as it were. But I'm not sure how outrageous it is that someone should leave pamphlets around the shelves of a library. In practice it would present problems, as the stacks were piled with material from competing viewpoints, so it makes sense for library policy and practice to forbid it. But I don't believe that A would have been as offended if she found pamphlets expressing views more congenial to her: on young women's health issues, gay and lesbian youth, riot grrl politics, and the like. She might have collected and moved them, but I don't think she'd have been as indignant. She might even have moved them to a place in the library where such outside material can be put for people to pick up.
But I was more concerned with her general assumption that she nor other people should have to encounter material that offends them in a library. A lot of people object to public preaching and missionary work, and that's admittedly a problematic case of freedom of religion, which has been much debated over the years. So has the question of public political speech that is offensive to many people. But these situations tend to be double-edged: the people who want to eliminate from their sight public speech and text that offends them, generally don't even think about who might be offended by publicly visible material that they agree with, but which offends others whose sensibilities they don't care to shield.
The matter of being preached to is something I've thought about before. In the first post I noticed that some secularists posted about their desire to deface religious billboards; in the second I noticed that liberal Christians and secularists threw hissyfits about seeing expressions of the beliefs of their more devout Facebook friends. (I'm sure those liberal Christians and secularists post a lot of their opinions, on politics and religion and other matters, without worrying about whether all their friends agree with it or want to be preached to by them.) I certainly share and sympathize with their fatigue, but I also recognize that being exposed to beliefs and statements I abhor is the direct result of living in a society which safeguards freedom of speech. I can only insist on my right to express my opinion because I grant others their right to do the same. I also insist on my right to talk back to people who express opinions that offend me (while acknowledging their right to talk back to me), and that really bothers many people from all over the opinion spectrum. Whether they be Tea Party Republicans, Obama Democrats, fundamentalist Christians, liberal Zionists, New Atheists, or really of any affiliation, they believe that "debate" means that they state their opinions boldly and no one may disagree with them. They often accuse me of being surprised when other people are bothered by what I say, but I insist they're projecting. I am not surprised when people disagree with me, even vehemently; I answer them back, and that pisses them off even more.
In my comments I hinted that I was concerned about A's intolerance of views she disliked, and one of her other friends accused me of crying "censorship." I snapped back that I hadn't said anything about censorship, but I admit it was on my mind. Would I really trust A not to impose censorship if she could? Frankly, I wouldn't. I remember a young woman who told a gay student group meeting that when she found a right-wing newsletter left for free distribution in the Student Union, she collected the whole pile and threw it in the trash. Or tried to; at this remove in time I don't recall if she complained that someone stopped her. The thing is, that newsletter was in a location of the Union that was intended for distribution of handouts for all kinds of organizations. Wouldn't she have screamed bloody murder if someone had thrown out the gay group's handouts? Of course she would. (Something much milder: when A was working in the dining hall, she had to be told not to set up her laptop to play music while she worked. That other people might not want to hear the music she liked not only didn't occur to her, I'm not sure it ever sunk into her head as a consideration she had to respect.)
Some years later numerous earnest young gay people tried to shut down the blog of a right-wing, fundamentalist Christian, antigay business professor; they failed, because the University stuck by the First Amendment, but they continued to insist that it was wrong for people to be exposed to "hurtful" opinions. There was also some talk about prospective students needing to see that the University is supportive of its gay students and "diversity" in general, or they wouldn't come to IU. I rather doubt that any school anywhere is uniformly supportive of all minorities, but IU has a lot of official material online declaring itself pro-diversity in general and pro-GLBT in particular. A blog, even a professor's blog, doesn't negate that. If I were an incoming freshman now, I don't know how I'd feel, but I think that at that age I recognized that it important to me that the University wouldn't shut down views that some people disliked. I knew from early on that I was a dissident and annoyed other people with my opinions.
In fact, these events made me wary about speaking up in public around the university; when I started this blog, a few years before I retired, I was nervous at first about using my own name, and of course I put it on a service unconnected to the university. I quickly got bolder again, but any attempt to silence unpopular opinions has a chilling effect. Before I started blogging, other gay people occasion tried on more than one occasion to remove me from Speakers Bureau, or to get the student newspaper to drop the opinion columns I wrote from time to time. Some such efforts came from raw undergraduates, but others came from people with positions in the University bureaucracy. This never had much effect on me, but it made me aware that I can't trust my fellow queers to respect diversity of opinion in their own community. So I have personal reasons, as well as principled ones, for my strict views on freedom of speech, press and religion.
This common self-centered inability to see or care that one's own views might offend others, or that they have the same right to be offended as oneself has, is extremely widespread. In my part of the opinion spectrum it's rationalized with such notions as that "hate speech" or "stereotyping" or "demeaning images" aren't protected under the First Amendment; but in fact they are, and it's my opinion that they should be. The First Amendment guarantees your right to be offended. In other societies you may be "protected" from ideas or texts that hurt your feelings -- but you might just as easily be silenced, to "protect" the delicate feelings of others.
Exactly where to draw the boundaries is another question, difficult and impossible to settle finally. I concede the library's power to keep uncatalogued material off its shelves, but only as long as it welcomes an offensive range of opinions and positions into its official collection. I was bothered, not by A's removal of the pamphlets, but by her self-righteousness about it. As she replied to me, she was entitled to be annoyed by them; I agreed, but I was also entitled to disagree with her.