I have thought this same thing for a long time.
One of the reasons I had a hard time believing 9/11 was an inside job was his reaction that day.
If he knew it was coming he could have arranged to look less like an idiot.
He was blindsided. They pulled it off without telling him and he has lived with that since.
They didn't trust him, so they didn't tell him.
I won't condone him or defend him. But he may have saved his own soul by cooperating.
Time will tell.