A Squared:
The raison d'etre for the "zoom upward" theory was to explain why so may people reported seeing something "streak" upward. It serves no other purpose, other than to provide an explanation for the witness accounts of a fire streak going up.
So to your knowledge there has been no scientific mathematical model applied on that animation?
As I said, and gave some examples of, nothing I have come up with even remotely resembles that kind of trajectory. In all calculations I have done, even when just considering the B747 as an intact plane just shortened fuselage by the length of the nose, the CoG inevitable goes backwards and causes the plane to stall after a very short period of time. Assuming all engines work completely fine* I do get some upwards movement, but not even in the range of thousands of feet.
But, as I said. These are all ballistic calculations and as we know that is a huge amount of drag that are not taken into consideration when calculating ballistic scenarios.
I have not made any drag (non-ballistic) calculations because honestly they are SOO much work!
*at the point of explosion and in some scenarios for 2s afterwards. I chose 2s completely arbitrary.