?? That explanation was not my invention....it was part of the explanation of the designers of the building and structural engineers. Why should your 'opinion' the "the core would remain" override them?

I don't have a complete answer right at hand...but my 'off the top of my head' image is of the roofs of the towers, with lots of machinery on them, not realizing they were supposed to avoid the cores.

(Smart alec answer? No... I mean that...and remember, parts OF the cores were damaged by initial impact...and all sorts of other stresses.)

Why not look for the answer to your question by doing a search as if you were on my side and trying to convince doubters? *I* am already convinced....*I* need a BETTER contrary answer to change my mind.