Well considering that the only real evidence that he was a poedophile is based on a hadith written hundreds of years after his death, and was reported by someone who is not ironclad reliable, then it is merely hearsay and not historical fact at all.

As for the drawing of him at all, you're not a muslim, you have no obligation to follow islamic ideas, so as long as you have respect for the subject and those that follow him, then I think that maybe you'll be in the clear. As long as you have a strong basis behind what you draw and can defend if anyone should challenge you.

Just draw him doing whatever to show them the world is not going to end

Like, Muhammad eating a cookie or whatever

The whole "don't be offensive" clause in the AUP and the TOS rubs me the wrong way. It's so absurdly subjective and can only end up being inconsistently enforced. Skoon made a good point in his journal that's worth repeating: what about other more fringe stuff, Anubis porn for example? That would be quite offensive to those believers, if they weren't all dead. Hell, perhaps there are still some people that think the ancient Egyptians got it right (FSM help them), who would be legitimately offended, but I have no doubt they'll get dismissed as absurd should they mention it. And it's not hard to think of other examples.

Well, it's a double standard. Giving a bunch of suicide-bombing terrorists special treatment seems a safer thing to do, but at the cost of social freedom. It kind of negates the whole idea of the event - "these terrorists can't silence us with their death threats. Oh but wait, keep it PC! I don't want to receive death threats!"