Feminism and possible racial differences seem like pretty low-value discussion topics to me...
That's an incredibly short-sighted attitude. Feminism and race realism are just the focus of the current controversy. I'm pretty confident that you could pick just about any topic in social science (and some topics in the natural sciences as well - evolution, anyone?) and some people will want to prevent or bias discussions of it for political reasons. It's not clear why we should be putting up with this nonsense at all.
My argument is: (1) Feminism and race realism are interesting for the same reasons politics are interesting and (2) they aren't especially high value. If this argument is valid, then for the same reasons LW has an informal ban on politics discussion, it might make sense to have an informal ban on feminism and race realism discussion.
You don't address either of my points. Instead you make a slippery slope argument, saying that if there's an informal ban on feminism/race realism then maybe we will start making informal bans on all of social science. I don...
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.