I'll comment on the quotes Wei selected (this isn't meant to be related to anything else here, just isolated reaction to Wei's drawing attention to these things):

But whatever our intended meaning of 'ought' is, the same reasoning applies. Either our intended meaning of 'ought' refers (eventually) to the world of math and physics (in which case the is-ought gap is bridged), or else it doesn't (in which case it fails to refer).

It's easy to construct all sorts of interpretations that could be said to be referents of anything else. The question is not well-defined on the level where we talk about "referring" and not including more powerful means of constraining what kinds of "referring" are relevant. Correspondingly, "failing to refer" only makes sense relative to a method of interpretation, and in the case of normative value, discovering correct method of interpretation (relevance-guidance) is more or less the same problem as discovering the referents.

It suggests that there is no One True Theory of Morality. (We use moral terms in a variety of ways, and some of those ways refer to different sets of natural facts.)

We might use moral terms in a variety of ways, but maybe still we should use them in One True Way, in which case there is still One True Theory that describes it.