Albion's seed is pretty much entirely focused on culture, laws, and institutions, not genetics. I'm not sure how this is supposed to be related to human biodiversity at all.
And on a final note, I'd suggest you read the last paragraph of the screenshotted email chain, where Scott explains how it's valuable to read creationist arguments it forces him to sharpen his thinking.
> You never realize how LITTLE you know about evolution until you read some Behe and are like, "I know this correct... But why not?".
> Even if there turns out to be zero value in any a Reactionary has ever said, by challenging beliefs of mine that would otherwise never be challenged they have forced me to clarify my thinking and up my game.
I really think you've lost the forest for the trees here. Scott is praising certain parts of reactionary ideas for asserting things most people wouldn't argue, and those interactions are leading him to sharpen his thinking.