Kempe,
Nist merely assert that progressive collapse caused the fall of WTC7. They didn’t model it, or even describe it. They offer no proof.
OTOH, the UAF report demonstrates why it <i>couldn’t</i> have been progressive collapse, and offers for examination all the modelling, engineering, mathematical and physical evidence on which they base their conclusion.
It doesn’t matter whether progressive collapse can sometimes cause the collapse of some buildings. We now have <i>evidence</i> that it couldn’t have been the cause of WTC7’s fall. Now it is up to you to refute that evidence, or accept it.