The actual physics behind the collapse are well explained
You clearly have misunderstandings of 'the official explanation' and the physics involved if you think that for a building to collapse upon itself all sides must have been equally weakened.
Okay well what I pulled from the Northwestern document why it didn't topple over was because
"Before disappearing from view, the upper part of the South
tower was seen to tilt significantly and of the North tower
mildly. Some wondered why the tilting did not continue,
so that the upper part would pivot about its base like a
falling tree of (Baant and Zhou 2002b). However,
such toppling to the side was impossible because the horizontal
reaction to the rate of angular momentum of the upper part would
have exceeded the elastoplastic shear resistance of the story at
least 10.3x( Baant and Zhou 2002b)."
just trying to think about in layman's term and can't really understand it because I don't know what elastoplastic shear resistance is or how they would even calculate that.
Now check it out on video at 20 secs in: