On the Shoulders of Settler-Colonialists

Here's a question: At what historical point do "colonizers" become "immigrants"?

This morning on Democracy Now! a New Zealand Muslim scholar discussed, among other matters, the history of Muslim colonists there.  Apparently the first known Muslim colonists arrived in New Zealand in 1850, about a decade after the first British invasion force.  She didn't use those terms, of course; I believe (it's too early for the transcript to be up) she used the term "immigrant."

Yesterday someone posted on Twitter something to the effect that there are no "settlers," only "colonists."  I think this was meant as a comment on terms like "settler-colonialist society," used to describe countries like the United States, Australia, Canada, Israel, South Africa, and New Zealand.  Apparently the tweeter considered "settler" a relatively neutral term, though I don't think that's the case in "settler-colonialist"), and "colonist" the hard word that speaks truth to power.  So I began wondering about the status of those first Muslim colonists in New Zealand. True, they weren't the initial shock troops, they followed in their footsteps as it were; but why, if the British were invaders (as they were), why were those who followed under their aegis seen as somehow legitimate, even innocent?

This is not, of course, to imply that the Christchurch massacre was justified because Muslims are invaders; very much the opposite.  (If I had meant to imply such a thing, it would mean that massacres of "white" settler colonialists in New Zealand and Australia, inter alia, would also be justified.)  As the DN segment made clear, many of the Christchurch victims were refugees.  But as many critics have noted, the "nation of immigrants" motto is problematic for settler-colonialist societies.  I raised the same question a couple of years ago about a Canadian Muslim college student who overlooked her own dubious status as a settler-colonialist polluting "sacred" First Nations soil.  She seemed to assume that she stood with the aboriginal inhabitants by virtue of being a person of color, though I doubt she'd thought that deeply about it.  She herself has massacred no Natives, but she stands on the shoulders of those who did.

What I am saying is that evidently at some ill-defined point, the non-Polynesian settler-colonialists in New Zealand, or their descendants, seem to have metamorphosed into a nation of immigrants who are entitled to welcome yet more settler-colonialists as immigrants to the land their ancestors stole.  I am genuinely curious to know what that point is.  There is a great deal of confusion about this, and I'll try to explore it further soon.