"What does in fact happen is that the top section breaks up internally so that it no longer behaves as a rigid object, relieving it of the obligation to conserve angular momentum"

Not exactly, (that's a pretty sloppy 'layman translation' explanation) the energy expended in the disintegration lessens the angular momentum (conservation of energy).

"By turning into a slurry of concrete dust and shattered steel the rotation becomes dissipated into the motion of what is essentially a fluid."

One (slower moving due to the breakup) fluid in another, air, which means that it is braked in its 'rotating motion', and starts to drop straight down under gravity.

Why does it "break up" - Well, 'Fiscs Majer', you obviously can't understand that either. That's already been well explained to those who want to understand.

You pretty obviously are 'cutting and pasting' stuff you cannot understand, or misunderstand, or even deliberately 'pretend to misunderstand', just to 'stir'.

The fact that your writings here demonstrate that you clearly cannot understand the science, as displayed by your questions and responses, reveals you as either an ignorant uneducated fool, or an intentional malicious trouble maker, trying to have some 'fun'.

The fact that you wish only to be an anonymous GUEST, only being forced to have many 'clever names' now to stop being deleted, adds weight to the second.