I had exactly this question when they mentioned that Osama was killed and his body thrown to the ocean. OK it's not a drowning, but why was it thrown to the ocean?
Because they didn't want to create a site that could either be turned into a memorial (by sympathizers) or a target for vandalism (by people who hated him), or both.
In any case, if you're wondering whether or not bin Laden is dead, you can be pretty sure that he is. If he weren't, the best way for them to damage and discredit the US would be to post video proof-of-life. The fact that they haven't done that by now shows that they can't.
But I agree, Occam's Razor. That being said, cremation and don't tell anyone where the ashes went.