The idea of mind independent prescriptive facts seems incoherent, it doesn’t even pay rent, even if a stone tablet has the moral commandments written on them it still doesn’t give me a reason to pursue them. Moreover it has no pragmatic implications, let’s say even if I presuppose there is some essence of morality, evolution has no reason to converge on it. This essence of morality is also not needed in our physical models to draw predictions, so might as well remove them—because occam’s razor. Moral anti-realist theories are able to explain the moral intuitions just as well whilst still being epistemically coherent,positing less laws and tenable.
Now you can argue there are certain things which humans in general can value more or less than others given the machinery of the brain—that would be an epistemic claim, but that does not require queer mind independent objective moral facts.
I haven’t looked much into AI doom, I still find some posters here useful. Just to note a lot of AI doomer criticism posts do get a lot of upvotes if they appeal to the attitudes of lesswrong users.