Disappearing into dust does not mean it was turned into dust. Shake out a very old rug, and it (and you) will disappear into a cloud of dust in the same way. The rug is not destroyed, you just freed a great deal of material from it with a blast of air.
A structural collapse also creates a blast of air, which frees an immense cloud of dust without actually destroying a great deal of the building itself. Light and fragile materials that like insulation, drywall ceiling tiles, cheap furniture, soot and smoke from the fires, stored dry goods (everything from paper to coffee in the break rooms) will all contribute to the dust cloud while comprising a small fraction of the building's weight.
If the entire top few floors were turned into dust, the cloud would have been orders of magnitude larger and the energy needed would have been much, much greater. Even explosives and thermite could not have done that.
Now, to the antenna: The antenna moved before the wall collapses because the buildings had a design that was called "tube in a tube
." There was a strong central structure with most of the utilities (elevators, water, electricity) running through it, and a strong external structure bearing most of the weight, with structure between them for stability and to hold floors and such. At the time it was revolutionary, only a few buildings had been built this way before. Because the "guts" of the building are weaker, the external or internal structures won't necessarily collapse together, the structure between them offers little resistance if they move differently. Those guts also provided all the stability - neither structure could stand on its own without the connections to the other, meaning not only could they move independently, with their connections damaged they probably would move independently.
Nobody's debunked Newton. They've debunked the grossly incorrect measurements in your expert's chart, and the gradeschool level of physics he applied to them. You can simplify the forces on a simulated building in a lot of ways, but breaking it down into a solid box of uniform density or worse yet a series of inelastic point masses is way below the bare minimum.