cognitivist, which is often grouped against realism
Is it? That seems backwards to me: non-cognitivism is one of the main varieties of non realism. (The other being error theory.) What am I missing?
You're right, not all cognitivists are anti-realists. But some are, including Eliezer.
Indeed, realists are generally considered cognitivist. But my impression is that if a moral system is labeled cognitivist, the implication is that it is anti-realist. That's because realism is usually the top level of classifying moral systems, so if you're bothering to talk about cognitivism, it's because the system is anti-realist.
There seems to be a widespread impression that the metaethics sequence was not very successful as an explanation of Eliezer Yudkowsky's views. It even says so on the wiki. And frankly, I'm puzzled by this... hence the "apparently" in this post's title. When I read the metaethics sequence, it seemed to make perfect sense to me. I can think of a couple things that may have made me different from the average OB/LW reader in this regard: