Here we go...
I didn't blame the cartoonists. I'm just stating the facts of the matter and the facts of the matter is this:
When you have extremists (whether it be militant muslims or militant christians) and you do something they consider an affront to their extremism, they're going to act predictably.
An anti-choice extremist is predictably going to do something extreme when it comes to abortion clinics, doesn't make it right but it's, sadly, a fact. We've had enough incidents to prove this out.
This cartoon convention is the same thing. The Islamaphobes created a convention, that they knew had the possibility to incite violence (they spent 50k extra on security), and violence happened. It's logic (or causation), not blame. If you yell fire in a packed theater people are going to run.