black people should only do black people things” and “white people should only do white people things”, which is an absurd position to me.
Close, but not quite spot on. As with everything that social justice touches, they try to frame everything in terms of power dynamics and marginalization. They define all their negative terms by way of relating them to these power dynamics, which really just allows them to ignore behavior from non-whites. This can be seen in redefining the word racism to mean prejudice + power so that, definitionally, black people cannot be racist because they don’t have systemic power.
The same is done for cultural appropriation. Whites should only do white things, but blacks can do white things as well, it’s not cultural appropriation when they do it.
It’s rather eye opening when you spend some time going through SJW ideology and realize the extent to which, according to their own definitions, white people are the only ones capable of embodying the negative behaviors they decry. It’s a neat little trick to fool dumb people.