I think the CML incident and the time where he yelled at some Debian developer about "our tribe" are better examples, because at least there he's going into other people's spaces and actually confronting them.
He's not an academic researcher. Don't you think it's odd for some old white guy to get worked up over minority test scores? Why write about this rather than basically anything else? Either he's a troll or profoundly unaware about how bringing this line of argument up may make people feel threatened. There are a lot of things that simply don't need to be discussed. It's like graphically describing your partner's episiotomy over dinner. Some things just inspire a visceral reaction.
Here's an unflattering guess why he might be interested in this: he has cerebal palsy. Despite that, he still is a fairly smart (even if crazy and/or racist) guy. He might be extremely interested in differences in human intelligence for that reason. To figure out why he still has above average intelligence while most other people with his birth defect don't. That could explain a lot of his crazy beliefs and his narcissistic "I'm a super unix hacker" routine.
Why does he have to be an "academic researcher" to have opinions about race that he wants to talk about on his blog? Or for that matter, any topic? Do you have an anthropology degree to assert your opinion that his blog may make people feel threatened, or are you just another guy on the internet with an opinion?
Why not? If it's true, and you offered absolutely no refutation to his claim whatsoever, why shouldn't we discuss facts? Do they stop being true if we stop talking about them? Do their ramifications stop existing if we just refuse to accept them?
Er, why do we think there are no black people reading his blog?
Even then, that quote isn't a individual indicitment of stupidity. Something which there are many examples of him doing, more aggressively, in other contexts.