Let me try a different tack in my questioning, as I suspect maybe your claim is along a different axis than the one I described in the sibling comment. So far you've introduced a bunch of "moving parts" for your metaethical theory:

• moral arguments
• implicit reasons-for-action
• effective descriptions of reasons-for-action
• utility function

But I don't understand how these are supposed to fit together, in an algorithmic sense. In decision theory we also have missing modules or black boxes, but at least we specify their types and how they interact with the other components, so we can have some confidence that everything might work once we fill in the blanks. Here, what are the types of each of your proposed metaethical objects? What's the "controlling algorithm" that takes moral arguments and implicit reasons-for-action, and produces effective descriptions of reasons-for-action, and eventually the final utility function?

As you argued in Unnatural Categories (which I keep citing recently), reasons-for-action can't be reduced the same way as natural categories. But it seems completely opaque to me how they are supposed to be reduced, besides that moral arguments are involved.

Am I asking for too much? Perhaps you are just saying that these must be the relevant parts, and let's figure out both how they are supposed to work internally, and how they are supposed to fit together?