Again, we should find somewhere else to discuss this- but (if that's indeed Eliezer's quote) it couldn't be unthinking bias; the idea of moral concern universalized to all sentients was a big theme with Young Eliezer, if I recall correctly. Some further argument changed his mind, at least in the context of some pertinent query.

And I'm not among them, but there are a fair number of Less Wrongers who are vegetarians for ethical reasons.