The idea that a plane would hit a major skyscraper, in a pre arranged way, so that carefully positioned explosives could then bring it down in a controlled manner....with no one involved saying anything 10 years later....is unlikely.
Highly improbable.
Unless.
Unless, who knows? Bob, people stop themselves from doing things with self limiting thoughts. What if these self limiting thoughts were applied to thinking about making something like this happen? What if your socialization against thinking evil things makes it impossible for you to imagine REAL ways to do evil things? It always goes back to Megadeaths for me. What are people who think in Megadeaths capable of? Can you even imagine being in those shoes? What kind of mind does it take to think that way? What else are they capable of?