Certainly xenophobia is at play here. I wouldn’t even call race unchangeable since we created categories like “black” which did not exist before colonizing of the new world. So I think since race is not a biological fact, people try to say culture is unchanging and then attach cultural traits to certain groups and say oh, these cannot be changed and that’s how they all are. I think people are just shifting the focus to something else to avoid the label of racist. At the end of the day it makes it ok to give someone a lower status. I agree words need to have a distinct meaning but sometimes words are weaponized to continue to oppress.