Depends on your value system
It seems odd that an absolute would depend on something subjective, doesn't it?
we would not be able to trust each other.
That sounds like a pretty utilitarian concern to me, rather than a contradiction.
>It seems odd that an absolute would depend on something subjective, doesn't it?
Go deep enough and eventually everything is subjective. Even things like fundamental axioms.
Explanations.
That there exists more than one explanation for a phenomenon, like ethics and moral values, doesn't mean that choosing any of those at random yields a good explanation. It also doesn't mean that there is no valid explanation at all.
That's just lazy not-100%-sure-therefore-I-substituite-my-own-reality-ism.
This, for example, suggests that lying is absolutely immoral, because if lying were universally accepted as good, we would not be able to trust each other.