You have a point; one I've considered in light of the De Menezes shooting here in Britain, i.e. how can no-one be to blame for the death of an innocent man? Failings were identified in various aspects of the overall operation and the execution of the tactical side of things, yet AFAIK, no-one has "copped it"; not the officers involved (rightly so IMO), and no-one in the chain of command (wrongly IMO). The buck should stop somewhere. However, the difference is that the UK authorities were directly responsible for De Menezes' death. If the US gov is not directly responsible for 9/11, the need to root out and eliminate the culpable is not as great.
I think it's a valid question - who should be held responsible, and how? But it does not lend any weight to any CT having taken place.
Yes!!! And I'm not saying it proves anything related to CT.