I have to agree with Citan. Bowing doesn’t always mean you’re being submissive. What about when people bow to greet one another (this also applies to curtsying for females)? Bows can be used to express different emotions, it’s not always about submission.
I’m not ruling out the possibility that Obama performed the wrong gesture for the situation he was in, but of you are completely ignoring the other reasons that one person may bow to another.
Actually, cross out what I said about ethnocentrism (though some of it seems to apply here) and replace it with jingoism.