Yes, I think it is based however, on a full compliment of engines running at say, cruise power, and an attitude that wouldn't be that much of a change when hurriedly pulling to +5. The power increment could then be metered out by erm, skilled judgment.
The crew were perhaps dealing with not only vigorous turbulence, but also more than a few man-made excursions from the horizontal. Also trying to recognize a stall with massive lifting and down-droughts would certainly be very much more difficult. Stalled one moment, and flying with reduced wing loading the next.
What I find hard to understand is the 'Deep Stall' nature of this decent. There does not seem to have been a succession of conventional stalls, yet the aircraft is not one of the T tailed types that could lock one into such a decent. I can only conclude a lot of time was spent with the systems blurring the issue, indeed applying power with vectored thrust 'shaping' the angle of stabilization to some deceptive angle.
Is there a clear recording of the flight-deck ambient noise? Once height was reduced enough to give a good gap between stall speed and overspeed, the ambient noise would have been quite different. The silence should have been deafening.