In any case, the general point I wanted to make can certainly be made in a formally correct way as long as you don't insist that every rational intelligent being must have the same utility function.

Certainly, when there is a genuine disagreement in utility functions, it is not reasonable to claim one's own terminal values as privileged (in debate, that is; it is reasonable to personally act on one's own values), but this does not apply when one's stated values are not their terminal values. And it is reasonable to question whether this is so, to try to distinguish the two cases.