Drawing an image of Muhammad is analogous to verbal insults in that the motive for doing so is to offend others. What might a respectful or otherwise inoffensive depiction of Muhammad look like, and what would be the artist's motive for creating and disseminating it if not to be offensive?
This is where it falls apart. Muhammad is a historical figure. His life and his actions are a part of the historical record; unlike Jesus or Buddha, who are difficult to provide good historical evidence of and who left little trace to mark their steps, Muhammad's life and times are imminently important in understanding the history of the Arabian Peninsula. Depicting him is, as such, entirely possible to be educational, nationalistic, inspirational or negative propaganda both, or simply a personal tribute by the artist to a man who left an exile, returned a conquering hero, and founded one of the world's greatest religions.
The depiction of the two pivotal events in the existence of early Islam, the flight to Medina and the return to Mecca, could be any or all of the above things.