> It's also just assumed immigrants themselves don't have cultural preferences when it seems they do

Of course we do! We don’t even pretend otherwise. I went to a Bangladeshi wedding in Toronto a couple of years ago. A friend of the groom’s family said to my dad that it was too bad my brother and I couldn’t find Bangladeshi women to marry. This is probably not the median view among Bangladeshis in Canada, but it’s within the Overton window—to the point where our response to this comment was to say something ambiguous about the place where we live having few Bangladeshis. And most Bangladeshis I know still marry within the community even in the U.S.

But of course there is a double standard here. Brown people aren’t treated as having moral agency. Bangladeshis in America can express extreme in-group preference and nobody will say anything. But it’s utterly taboo for whites to do the same.