The reality is that there are somethings that people will kill for. If you were to see a child killed before your eyes, or even see something you cherish destroyed before your eyes, you would DO something. If a Muslim were to see the pages of a Koran depicted as toilet paper, then he would DO something. Given what he believes the Koran to be, it would be far worse than Mapplethorpes puting a crucifix in a jar of urine and calling it art.
The reality is it's a cartoon and Muslims are nuts.