Interesting data. The ARTCC (FAA enroute radar) would have tracks of everything that was in the air, at altitude, at those times.
However, I'm skeptical for another reason: The pilot(s) and the chain of command involved in any such shoot down order would be a source of leaks by now. IMO.
I do not think a pilot who shot down FL93 would be eager to have his name associated with their deaths. Particularly if the was a chance the FL93 heros might have been able to pull off their coup if the shootdown had not occured.