There will always be rude people who go out of their way to insult other people's faiths. They might even do so in ways designed to provoke. (Hopefully this issue will die with a whimper, as the pastor reconsiders his unwise plan of action.)
The question then is how the world should respond to such provocations.
Repudiation, accompanied by clear expressions of support for those who are targeted, strike me as the appropriate response. Public protest such as marches--as long as it is respectful of other people's faith--is appropriate as well, should one feel so moved. However, violent response is entirely inappropriate. That is an irrational and repugnant reaction to a despicable act. Indeed, a violent response is far worse than the original action on a moral scale.
Perhaps some utilitarians would disagree. They may say that the morality of the burning, if predictably followed by a violent response, must then be presumed to subsume the ill effects of the violence. I would think that the moral guilt of provoking violence should be borne by the person lighting the flame, but that this does not mean that that person is as morally reprehensible as the person engaging in the violence itself.