most hilarious thing about the whole muslim anti-iconography is that the purpose of not having pictures of the prophet is to prevent idolatry. this is clearly quite the opposite and are in effect idolizing the prophet by demanding no one make fun of him
also -- in iran you can find pictures of mohammed. the quaran condemns idolatry, that's it. rules may have sprung up around that getting rid of any pictures of humans (see for example the desecrated hagia sophia, or how the taliban banned photography) or specifically the prohpet but shia muslims don't agree