The burning flag was wrong at all events.
Was it? Some people on the far right accuse Mr. Obama of either being virulently anti-American himself or else connected with (or at the very least aiding and abetting) those who are. Some of the latter set routinely burn American flags. The caricature wouldn't have been complete (that is, at its zenith or at its nadir, depending on your point of view) without that crowning touch. It wouldn't have reflected current events, as it were, fully.
I tend to think that the cartoon stands or falls as a piece. The bigger issue for me is whether I'd want to live and speak in such a way as to provoke that kind of satire (fairly or unfairly, and directed either at me or at my critics) in the first place.
Just a thought.