Not necessarily, and in the case of "avowed racists of Less Wrong" almost certainly not. The "biological realism" concept is that there are genetic and physiological differences split so sharply along racial lines ("carves reality at its joints") that it is correct to say that all races are not born equal. Proponents of this concept would claim it is obviously true, and they would also be called racists. These people could donate heavily to African charities out of sympathy for what is, in their eyes, the "bad luck" to be born a certain race, and it would be consistent.
(I believe that biological realism is the main form of racism amongst LW posters, but I have nothing to back this assertion up except that I recall seeing it discussed)
but of sympathy for what is, in their eyes, the "bad luck" to be born a certain race
Or more to the point, sympathy for people with greater challenges than others, and finding that African charities, by targeting Africans, are more likely to target people with those challenges.
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.