In particular; it is unclear to me why Ought-claims in general, as opposed to some strict subset of ought-claims like "Action X affords me maximum expected utility relative to my utility function" <=> "I ought to do X", are relevant to making decisions. If that is the case, why not dispense with "ought" altogether? Or is that what you're actually aiming at?

Well I guess strictly speaking not all "ought" claims are relevant to decision-making. So then I guess the argument that they form a natural category is more subtle.

I mean, technically, you don't have to describe all aspects of the correct utility function. but the boundary around "the correct utility function" is simpler than the boundary around "the relevant parts of the correct utility function"

Would it be safe to say that your stance is essentially an emotivist one? Or is there a distinction I am missing here?

No. I think it's propositional, not emotional. I'm arguing against an emotivist stance on the grounds that it doesn't justify certain kinds of moral reasoning.