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:
In other words, prizing discourse without limitations (I tried to find a convenient analogy for said limitations and failed. Fenders? Safety belts?) will result in an environment in which people are more comfortable speaking the more social privilege they hold.
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.
For a bayesian who thinks about whether to hire a black person or a white one, it's irrelevant whether intelligence difference are due to parents being poor and haven't eaten enough food during pregnance or whether they are due to genetic differences.
As far as I understand the social justice movement they would approve of both justifications because both are essentially that the person gets judged by their background and get's treated as a member of an underclass.
I can't remember someone on lesswrong making a claim as strong as claiming that black should be stopped from procreating by eugenic measures. You find people who argue that overpopulation and African getting children is the central problem of humanity at the moment but nobody is making the argument directly.