Hanrahan, I understand the incompetence defeats conspiracy arguement, but the current village idiot of a prez would be kept safely away from any action, say in a school in Florida, reading to children, where he couldn't do any damage.
Only a few need to be in the loop, everyone else just follows orders.
Cheney was supposedly in charge of a massive anti-hijacking airforce drill that morning, the premise being hijackers have taken control of a number of commercial jets. Pretty neat of OBL to pick that exact time whereby the real hijacked planes would be virtually invisible because of these other fake hijacked flying around ( really they were fake radar blips entered into the system for the purposes of the exercise)and the air traffic controllers would be kept confused( which is what occured) so that fighters wouldn't be scrambled to intercept them. This was probably the key aspect to the whole thing, to keep the air defences on the ground (they did manage to get one plane though).
As you say, a pretty stunning coup, but who do you really think had a better chance of organising it, OBL in a cave in Afganistan with the assistance of 19 boys , or Cheney with the assistance of the of cream of the intel community?