When that American is a half-American involved in an organization that wants to kill Americans, we really shouldn't be surprised when said half-American gets killed . Not when that terrorist- yes, terrorist- cannot be reached by any other means beyond putting U.S. boots on the ground in the Arabian Penninsula.
What would you prefer? A dangerous special op raid into the middle of nowhere without help for hundreds of miles away so we can try to arrest a half-American who's only goal is to kill innocent people? Guess what; those guys doing those raids are too valuable and the situation can turn out to be far more explosive than a Hellfire missile.
Yes, we do assassinate Americans. Half-Americans to. Even bomb-makers. And like all countries, we have people amongst our population that are incredibly out of touch with their peers.
If Awlaki, the producer of Inspire, and the top bomb-maker of AQAP are indeed all dead than I will gladly have a drink to that victory. If people want to sit and moan about how stellar their ideals are and how wrong others are, that's fine with me too; you are, after all, entitled to be an idiot.