This is a farcical argument, because those scientists would have a basic understanding of biology, and therefore would understand that the notion of human "races" is an obsolete, antiquated and indeed, often racist, historical notion. Starting point for catching up: https://en.wikipedia.org/wiki/Race_(human_categorization)

Our host didn't call Yarvin a reanimated zombie Hitler; it was used as a generalisation (to absurdity) of the argument.

This long discussion of human "races" is awkward.