Okay... first, let's clarify... if the impact floors were removed, the remaining lower floors could have supported the weight of the upper floors, right? It was the energy released from the fall of the upper mass hitting the lower floors that caused all of the lower floors to fail, right? It wasn't the weight of the upper floors, right?
If the upper mass and impact floors were removed... than the lower structure would be perfectly stable and intact, right? It wouldn't be under any weird strains or loads, right? It would still have all the floors, trusses, core columns, out columns in great condition, and without any unnatural loads, right?
Just imagine... when they were building the towers.... and when they got up to the floors that were right below the impact points...they stopped building...leaving the top open and without a roof. Would this structure be vulnerable to any lateral loads?