Religious zeal as a political motive is still a political motive. Terrorism is terrorism. They may have, in your opinion, asked for it, but the very foundation of the concept of free speech is the idea that what one expresses in public may be offensive to some but should not give reason to anyone that they should die for saying it. They bore a reasonable expectation from their society that the worst punishment they would need to endure is ridicule - not death. Challenging a subculture that puts people to death for far lesser infractions shouldn't have to bear any weight on that expectation as long as their on their society's home turf.

Subsequently, passing out copies in Medina would be a different matter entirely and more in the neighborhood of "asking for it".