To put it as plainly as possible, if the proponents of the U.S. settler-colonialism theory are correct, then there is no basis whatsoever upon which to build a multinational working class communist party in this country. Indeed, such a view sees the “settler working class” as instruments of colonialism, hostile to the interests of the colonized people, rather than viewing all working and oppressed people as natural allies in the struggle against imperialism, our mutual oppressor.
A shame, a sad sad shame. For anyone that's read settlers, or knows about the history of labor zionism, or prioritizes any kind of indigenous voice in their praxis, this is really bad. No peace for settlers! Settlers cannot lead the revolution! I hope we see an end to any respect given to this "settler colonialism is over" politic soon.
I don't see where they are asking the indigenous to be subjugated. Best I can say is I think I understand your concerns and that their analysis may be clumsy in how it engages with people who may not even think of indigenous sovereignty at all in the first place and could take it as a reason to not care. I'm not convinced it intends to be doing that, it comes across to me more as the "programmer who thinks in code talking to the customer" trope of someone very analytical forgetting to think about the audience and how it might be taken, but I could be wrong.