However if a person has a webpage devoted to violent Muslim reactions, and declares that he's going to show them, and then publicly burns a Quarn and deliberately posts it knowing that it will be picked up and get broadcast in Muslim countries and parts of his own country in the hope that they will react violently, then that is intent.
And this hypothetical person would still be 100% morally inculpable in my book.
It's like the difference between running over a guy lying on the road in the fog and killing him, and running down a bunch of school kids on a crossing because they vexed you. The results are similar, but the first won't get you in legal trouble if you were driving safely, the second certainly will.
It's not even close to the same thing.
You're hung up on the classic "You can't shout fire in a crowded theater" benchmark and you're applying it in places where it doesn't make sense and worse setting a precedent that allows other people to site it in places where it doesn't make sense, again making the "Look at what you made me do" culture more prevalent.
The reason you can't shout fire in a crowded theater when there is no fire is because getting out of the way of a fire is a logical action and a reasonable person (and I mean that in the legal sense) should be expected to know what results would come of this action. You should fire in a theater, everyone's going to try to get out of it.
You're trying to turn it into "You can't say anything if you know the outcome is going to be violent (the difference between inciting violence and saying something you know will cause violence is meaningless) and you share the blame." and that's not the same thing.
Let's say you walk into a theater and before the show starts someone stands up and yells "I'm gonna punch the guy sitting in front of me if anyone in here laughs during this movie." Now you've already stated that anyone who laughs, since this guy clearly stated he was going to do it, would share in the blame in the earlier "Triscuit" analogy (BTW I call dibs on Triscuit Analogy as a band name...). They would not. Because punching someone because someone laughed is not a reasonable act.
Killing people because someone drew a cartoon is not a reasonable act. So the people who drew the cartoon don't share the blame regardless of any other factor. It's not the same as... a Grandwizard of the KKK telling his members to go out and lynch black people. One is a direct order the other is a reaction to a stimulus.
You're not creating an environment free of incitement to violence, you're creating an environment where threats of violence stifle free speech, where the violent among us can hold our free speech hostage.