Whether you agree with it or not, Obama's "moral progress" means a change in US law to comport more closely to (his present view of) morality, not a change in the moral views of Americans. It is quite possible to view oneself as the apex of possible morality and still believe in the possibility of moral progress on other people's part.

I disagree with Obama because I disagree with some of the goals of his morality, but I don't see that as any reason to attack his semantics.