I think Chris is slightly mistating the problem, at least on Lesswrong. It would be sort of shocking if various genetically distinguishable population cohorts all happened to be exactly equal in average intelligence. But that's not what's so off-putting about the reactionaries. The problem comes with their reliance on extremely lazy statistical discrimination in individual cases. They have made quite clear that if they encounter a woman or an individual of African descent who has tested very high on an IQ test, they would still discriminate against that individual for jobs or educational slots, arguing that racial/gender averages swamp the evidence from the test, which might just regress to the mean.
To me, the individual IQ test is much stronger evidence and should swamp the cohort averages.
Quite a number of people pooh pooh the reliability of IQ tests, most usually people in dogmatic denial about HBD. Are they also horrible people for their "lazy statistical discrimination"?
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.