"A Saudi national gives a tour of landmarks in Washington, DC that shows entrances, exits, and checkpoints" is not at all compelling, no. That describes my trip overseas last year if you swizzle the nationalities. The notebook of plane calculations is more compelling, and the evidence that he was paid by the Sauds as an informant is interesting, but not particularly damning (one possibility: he could easily be taking free money on the side while he coordinated with the Taliban outside of Saudi interests).
I'm inclined to agree with you. But I think that statement would apply to a blanket simplification like "The Saudis did it" also.