This is related to moral realism in that I suspect moral realists would be more likely to accept S, and S arguably provides some moral statements that are true. But it's mainly just something I was thinking about while thinking about moral realism.

I don't really know what I'm talking about when I say objective utility, I am just claiming that if such a thing exists/ makes sense to talk about, that it can only depend on the states of individual minds, since each mind's utility can only depend on the state of that mind and nothing outside of the utility of minds can be ethically relevant.