My feelings on the topic are similar to iceman's, though possibly for slightly different reasons.

What bothers me is not the fact that Eliezer's sex life is "unusual", or that he talks about it, but that he talks about it in his capacity as the chief figurehead and PR representative for his organization. This signals a certain lack of focus due to an inability to distinguish one's personal and professional life.

Unless the precise number and configuration of Eliezer's significant others is directly applicable to AI risk reduction, there's simply no need to discuss it in his official capacity. It's unprofessional and distracting.

(in the interests of full disclosure, I should mention that I am not planning on donating to SIAI any time soon, so my points above are more or less academic).

My biggest problem is more that he talks about it, sometimes in semiofficial channels. This doesn't mean that I wouldn't be squicked out if I learned about it, but I wouldn't see it as a political problem for the SIAI.

The SIAI isn't some random research think tank: it presents itself as the charity with the highest utility per marginal dollar. Likewise, Eliezer Yudkowsky isn't some random anonymous researcher: he is the public face of the SIAI. His actions and public behavior reflect on the SIAI whether or not it's fair, and everyone involved should have already had that as a strongly held prior.

If people ignore lesswrong or don't donate to the SIAI because they're filtered out by squickish feelings, then this is less resources for the SIAI's mission in return for inconsequential short term gains realized mostly by SIAI insiders. Compound this that talking about the singularity already triggers some people's absurdity bias; there needs to be as few other filters as possible to maximize usable resources that the SIAI has to maximize the chance of positive singularity outcomes.