Lesswrong has actually had such individuals show up here, too, from time to time. They get downvoted into oblivion and/or Eliezer or one of the other high-status people shows up and encourages downvoting people who feed the troll. So the racists who are just using biodiversity as a rationalization for already-committed racism get driven off.

This does seem relevant when answering the separate question of whether the topic should just be taboo.

To the extent that I've been involved in these debates on LW, I'm almost always arguing for the anti-racist and anti-sexist position, but I still wouldn't want Lesswrong to adopt the norms of discourse that prevail at "safe space" feminist sites. Because that way really does lie madness (I've seen a feminist website drive off anyone who wanted to dispute the claim "rape is worse than murder," to give one egregious example).