It's that love, pleasure, and equality are part of the definition of good, while paperclips are just part of the definition
And can aliens have love and pleasure, or is Good a purely human concept?
By Eliezer's usage? I'd say aliens might have love and pleasure in the same way that aliens might have legs...they just as easily might not. Think "wolf" vs "snake" - one has legs and feels love while the other does not.
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: