an organization who needs to hijack the weapons they use, or whose technologiocal sophistication involves truck and suicide bombs, or who sent their dirty bomber Padilla to gather hospital waste for material - doesn't have 20 pre-positioned nuclear weapons. It just doesn't line up.
I heard Osama actually has 20 paper bags of sh$t that he plans on setting on fire and leaving on the front doorstep of the White House.