The last sentence of the section agrees with you:

Unfortunately, we cannot know with certainty what the right decision is. Thus, the best we can do is to try to make "rational" or "optimal" decisions based on our preferences and incomplete information.

Yudkowsky-style metaethics emphasizes that "goodness" (or here, "rightness") is a property of actions that propagates from effects to causes, and this is consistent with the way the adjective "right" is used here in the FAQ.

Keep reading; it gets better.