Two planes are hijacked and then rammed into two of the tallest buildings in the world. Both buildings collapse, while causing another 3rd building to collapse as well. I'm not sure how a mathematical model would help/teach the terrorist any more than the already available public videos of the attacks.

The model may help terrorists destroy buildings without hijacking planes.

So could computers. Ban computers?

Good point but I think the planes were a crucial control for their simulation/modeling.

Using a truck in the garage in '93 didn't work. So they went back to the drawing board.

We all know what happened when the Rebel Alliance got the plans to the Death Star.

Better positioning and it may have worked...

It wasn't just a 3rd building, either - there was a lot that had to be demolished.

It sounds unlikely to me that some terrorists have figured out a secret way to collapse skyscrapers with an airliner that architects and engineers haven't figured out already and which wouldn't be part of the curriculum of becoming an architect or engineer in the first place.