From the very beginning, evidence for Osama bin Laden being the "mastermind" behind the WTC attacks has mostly been circumstantial. Sure, for his own ego he was willing to take credit for it, but there's never been much in the way of solid proof that his organization pulled it off. Most of the real research done to find the actual culprits discovered that it was apparently a loose organization of Saudi Arabians with their real leaders shielded behind walls of oil and money. They were able to find a willing stooge.

And now most people are happy and convinced that "justice" has been served, and they'll be happy to let the entire matter rest. Who knows if we'll ever figure out what really happened, and who really did what?