I can answer that. It was because he was scared. That's no indication of guilt.
That he knew two of the highjackers is no crime. Were they his buddies he hung out with? Was he in on the plot? Or were the highjackers just passing acquaintances?
If the Justice Department really had something on him they would have charged him with something. And no I'm not a bleeding heart liberal or soft on terrorists. If you think I am look up some of my other posts before you answer.