Thank you for an interesting technical description!
From a pilot's perspective.
As pilots, we have to ask, how did this happen? How did these crews get themselves so badly out of trim and why couldn’t they at least try to pull out of their dives? The answer is beginning to emerge that they could no longer control their aircraft in pitch!
Any time that a pilot flying such a plane with such a configuration (elevator and all moving horizontal stabilizer) senses that they are at risk of running out of pitch control authority they should get on the pitch trim in that direction first and ask questions later.
You came to the conclusion yourself. While you shouldn't control the aircraft with pitch trim, elevator input and trim wheel motion must come close together or control column forces will quickly become uncomfortably high. The QRH Maneuver section mentions pitch trim may be necessary for both Nose High and Nose Low recoveries.