this was months of work and analysis so anything here is going to be really thin. Unlike Sadam, Osama is not an egotist/narcassist. He believes in what he is doing. The disappearing Mullah legend is true (that the legend exists) So, with the strategic planning acumen that he has shown, it is totally logical to assume that he would realize that the one thing that would end his effort would be to be captured or proved killed. so, given that and given his committment to the cause, the surest way to ensure perpetuation of his effort is to disappear himself before any chance of being caught or killed. So, looking at what he knows, where he has operatives and plans and some other likily world events, he makes a few thousand sounds bites before laying under an incoming daisy cutter---
like I said, a lot left out but that is the thumbnail--oh, and the US look really proficient for years to come