Just a slight correction. Addis Ababa airport is at 7656’ above sea level, according to the preliminary report. I think the pressure altitude was around 5,000 at ground level at the time of the crash. They reached a maximum altitude of around 14,000’ above sea level, or around 7,000’ above ground level before the crash.
As I understand it, when the stick shaker/stall warnings are going off, and airspeed values are not agreeing, the tendency will not be to throttle back. One overspeed clacker kicked in around 2:30 before the crash, when one pilot was struggling to hold back the yoke, and the other was struggling with trying to move the hand crank stabilizer wheel. The checklist and additional advice from Boeing don’t focus on speed. They were still trying to work through the checklist at that point. The other overspeed clacker started later (the one on the right, which was the side with the more reliable instruments at that point.)
Now there is an emerging question about whether the elevator – the control surfaces that is providing the “up” force to counter the nose down stabilizer trim – suffers from “blowback” at high speeds. This would possibly explain why the final efforts to pull back on the yoke, which moved it back more than it had been pulled back the whole flight, did almost nothing. Blowback would mean that, at high enough speeds, the forces on the elevator are enough to overcome the hydraulics, and start to drive the elevator back/down despite the controls trying to move it the other way.
It may be easy to point to a few specific things in retrospect that could have changed the outcome. But it seems to me that this is exactly what simulator training is for, after there is a set, reliable procedure for the issue. Put the pilots in the critical scenario enough times that they can recognize it and respond reliably in the correct way, including knowing what to focus on, and what can wait until the issue is resolved.