Right, they weren't muslim, that's why they were using muslim IDs instead of IDs that would have been more appropriate to their oh so obvious All-American looks and accents. /sarcasm>
So it hasn't occurred to you that the real hijackers may have stolen identities that they knew the FBI would trace back to Osama Bin Laden? This could be part of some intra-Arab turf war, with one faction trying to incriminate the Ladenites.. and what better way to do that, than to piss off the strongest nation on this planet?