You have to understand a few basic facts, then unravel the mess from there.
If the passenger planes that took off from Newark, et al, could not have withstood the physical forces of flying that far above VMO, and yet still perform extraordinary turns at those speeds, then it stands to reason that the planes that hit the towers and Pentagon were not the original passenger planes.
The unraveling of this fact, and it has to be a fact - if for no other reason than only a modified and reinforced aircraft could withstand the forces imposed - then it further stands to reason that the passenger planes were "swapped out" midair with modified and reinforced drones.
This is not only plausible, and likely, it has historical precedent, at least in terms of operational proposal in the Pentagon plan named Operation Northwoods.
Northwoods was presented to John F Kennedy in 1963, and it is basically the same scenario as what played out on 9/11.
Swap passenger jets out with similar looking drones in midflight, crash the drones into targets, and blame "terrorists" to manipulate public opinion, etc.
From there, it also makes sense that the original passenger planes were landed (there is, or was, evidence that this took place somewhere in Ohio), the passengers disembarked and sequestered (the phones calls were conducted at this time), and then they were all killed. Gassed would make the most sense. Kills them all at once, no trauma for the killers.
To be sure, that is how I would have set it up.