So far - and I may have missed it - all the discussion has postulated a sudden pitch-up on encountering an updraft. Running some numbers on my calculator, I see that an aircraft at 480 kts, entering a 100 kt updraft, would experience about a seven degree change in the relative wind (equivalent to a seven degree increase on AoA) without any attitude change at all. Presumably this would result in a sudden gain in altitude and loss in airspeed without much sensory input for the pilots.
Is this a reasonable scenario, and could it have been disorienting enough to have contributed to a loss of control?