Re:
The short answer is I don't know, but I am proceeding under the following assumptions
"When you have eliminated the impossible, whatever remains, no matter how improbable, is the truth."
(A.C. Doyle)
"Facts do not cease to exist because they are ignored."
(A. Huxley)
...and my corollary to this:
"Those same ignored facts are often extremely significant."
In my opinion, the true circumstances of the events of 911 remain a mystery. However, this tragic event contains a number of characteristics, to say nothing of ignored facts, which may provide significant clues for those who have done their homework.
sp