Yes, I know there is linkage. I would agree the question "did Muhammad even exist" is a valid one but after that Mr, Spencer and I would likely part company as I also accept for the most part that the Jesus described in the 4 gospel narratives is also mostly myth.
Drawing pictures of Muhammad is IMO on the same level of silliness and lack of intellectual sophistication as putting a statute of Jesus in a glass of urine and calling that art. Just as those who support or defend either one IMO also for the most part equate to the same. I find no intellectual value in either.
Instead of screaming like hysterical little schoolgirls or acting like non thinking brutish little boys, why not dare to study the deeper origins of the belief system and then expose the underlying fallacy of said belief system that way? Problem is IMO, doing so would open up the fallacy of the other dominate monotheistic belief and expose it to the light of day!
Religion, from the latin religare: to bind, to restrict........To Cage?