harsh as it may seem, Casseia's message is (I believe) intended as constructive criticism.  I really don't want to break this down point by point as you've done, but suffice to say, my intepretation of "unsupported assertions" are the following:

"had to have been pre-fabricated."

Whose to say the damage wasn't caused by a front end loader stabbing the cab with a pole on the spot at the spur of the moment?  Unlikely, yes, but personally I don't believe it "had to have been pre-fabricated" although admittedly I didn't see the damage with my own eyes.  But with the necessary equipment on hand (at the nearby construction site?), a lot of things can happen on the spot.

"Furthermore Lloyde does not behave as someone who was unwillingly involved. If that was the case he'd be scared. He is not remotely scared, is clearly happy to talk about his experience with a big smile on his face"

Some people behave differently in situations of guilt, shame, etc.  He should be scared to talk to anyone, but perhaps his guilt drives him to do so?  I can't really explain his behavior but I also can't take it as proof of guilt; evidence perhaps. Like you said, someone should bring him in for further questioning, polygraph, etc.

"The notion they would shoot at some random old man and then immediately coerce him into calmly participating"

This was 9/11, why would anyone need to behave calmly?  That it happened to be his demeanor is not proof of complicity.  In my hypothetical scenario, he was relieved to have no bullet in his head and to know he had been adopted by the team that was in control of things.

The damage to the cab does not preclude a gunshot.  Kicking out the windshield would be a lot easier with a bullet hole for a starting point.  But seeing the dash and seat makes me think this was done with some heavy equipement.

Lloyde knows full well what he did on 9/11 and he is not the least bit ashamed or nervous about it.

It doesn't make sense that he's not nervous about it.  On the one side is truth and justice and possible treason charges, on the other side are murderous masterminds who control a lot of lives that would just as soon give Mr England a one way ticket to Jimmy Hoffa-land as let him point fingers at cutouts. So his behavior does not make sense.  He should be nervous from one side or the other, or both, why he isn't I would ask you to hypothesize.

Anyway, my message is to please take Cass's post not as a hostile assault but rather as a worst case analysis of your discourse style. I'm pretty sure we're all on the same side.