Human biodiversity is an empirical fact. Are some populations taller than other, on average? Is red hair more prevalent in certain populations? Pretty much nobody actually rejects the idea of human biodiversity.
The neo reactionary types tend to draw specific conclusions from the idea of human biodiversity, like that racial disparities in IQ are inherent and not environmental. That's a conclusion I don't think is in line with Scott's views.
Furthermore, I suggest you read the linked emails in more detail. He likes the emphasis reactionaries put on social class, and dislikes
... pretty much everything else. He explicitly states that becoming a reactionary is stupid - I'm not sure how that's meant to be read as sympathetic.
This is another case where praising even a small component of a particular movement, even when paired with explicit condemnation of the movement as a whole, is taken as an endorsement.
