So, a robust updraft. Very warm, sufficient to corrupt Mach value? Unless the increase in VS is due baro, then it is airmass. The point is, the a/c was out of phase, and the pilot was given an a/c that was climbing with the NOSE showing low. His Pull was additive to an input made by AutoPilot("STALLSTALL"), and the confusion began. Yes, he should have been "ready", and managed a better get than he did.
The problems encountered were not complicated, but the timing was.