The cartoon strikes me as tragically accurate. Islam rose from a society in which pagan idolatry dominated religious concepts. Worshipers of stone idols murdered Mohamad's early followers, with the intention of killing them all. The idolators would have succeeded in that goal, if the early Muslims hadn't fought back. So there is a very strong Islamic prohibition against idolatry. Idolators were the mortal enemies of their religion, in terms of religious belief but also in terms of life and death. The purpose of prohibiting images of Mohamad was to prevent such items from becoming objects of worship, to prevent people from worshiping icons of Mohamad, which would in effect be a form of pagan idolatry. Muslims did not want Mohamad to become some kind of god in people's minds.
The people rioting and murdering over published images and alleged disrespect appear to be doing something very near to that, elevating Mohamad into someone irreproachably above humanity. From what little I know of the man, he objected to people thinking of him that way.