Zorin
The first input was nose up. You are certain the a/c was not pointed down at this point? A NU input would be an attempt to level, if the a/c was PITCHED NOSE LOW. You also do not know the decision was not made that the safe conduct of the flight was in jeopardy?
This also ennables a further explanation of what occurred next, a lag in a/c response to the NU.
(at STALL)
"PITCH reduction to 5 degrees" . PF may have reduced his back pressure, but been unsuccessful at reducing PITCH. The a/c at STALL WARNING was at 6 degrees PITCH UP, so holding altitude at that attitude would be read by the Computer as a "stick back". Remember, up to this point, He WAS holding NOSE DOWN inputs. (Until STALL WARN).
Lastly "Why trim for NOSE DOWN when inputting NOSE UP"? He was NOT necessarily inputting NOSE UP, he may have been attempting a hold on to the altitude.
Also, he was not looking for TRIM, he was looking for AUTHORITY. He did not know the THS was full UP, and that he desperately needed to move it DOWN.
This is a gripe of mine. At unusual Attitudes (sic), why is the THS allowed to (commanded to?) migrate into a position where, if setting is unknown, it may be causing the problem PF is trying to solve?