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).
waves
Am I going to be "downvoted into oblivion"?
A long blog post explains why the author, a feminist, is not comfortable with the rationalist community despite thinking it is "super cool and interesting". It's directed specifically at Yvain, but it's probably general enough to be of some interest here.
http://apophemi.wordpress.com/2014/01/04/why-im-not-on-the-rationalist-masterlist/
I'm not sure if I can summarize this fairly but the main thrust seems to be that we are overly willing to entertain offensive/taboo/hurtful ideas and this drives off many types of people. Here's a quote:
The author perceives a link between LW type open discourse and danger to minority groups. I'm not sure whether that's true or not. Take race. Many LWers are willing to entertain ideas about the existence and possible importance of average group differences in psychological traits. So, maybe LWers are racists. But they're racists who continually obsess over optimizing their philanthropic contributions to African charities. So, maybe not racists in a dangerous way?
An overly rosy view, perhaps, and I don't want to deny the reality of the blogger's experience. Clearly, the person is intelligent and attracted to some aspects of LW discourse while turned off by other aspects.