Because of course he is.
If Khan's biggest booster, Steven Pinker, isn't ashamed to be associated with the neo-Nazi racist ghoul; and Khan's buddy Matthew Yglesias isn't bothered by Hanania's racism and extremism; you know Razib Khan's not bothered by Hanania's racism and extremism and neo-Nazism.
I think what all this means is that right-wing racist billionaires have increased their funding of ghouls like Hanania so much that courtiers like Pinker, Yglesias and Khan no longer worry about being "cancelled" because not only do they have the option of wingnut welfare - see Carole Hooven and Thomas Chatterton Williams - but their plutocrat patrons have decided to go full steam ahead in the project of mainstreaming race pseudoscience and racism.