Hi
AirRabbit
Presumably the angles mentioned in the report are from the FDR. To most people in the cabin 50 degrees bank will feel more like 90. Even the flight crew might initially overestimate the max bank angle they reached.
You're in a much better position to judge what really went on than me of course. I just enjoy technical debate.
I would certainly expect this aero model to be valid for all AOA's up to stick shake, but if you have significant sideslip as well, even at 7 degrees alpha, no commercial aircraft aero model is going to stand up very well. The 737 aero model had to be revised for just that reason after the rudder hardover incidents.