The PM was acutely aware of the planes attitude from the beginning. The CVR has multiple mentions of urgent "requests" to get the nose down. Combine this with the sharp initial climb and I fail to see how the PM was unaware of the cause and effect...he would/should have been very aware that the aircraft stalled.
I think that the airplane cockpit configuration made it much more difficult for him to actually know what SS inputs the PF was making. As events progressed I think this played into his state of confusion since the PF's actual inputs were not consistent with his verbal comments/replies. By the time the captain returned to the flight deck the PM's state of confusion had reached a point he was unable to
communicate with any real clarity....however it is probably reasonable to assume that the PM needed to intervene early in the sequence (which he tried to do) to enable recovery.
At the end of the day the Captains decision to place the least qualified officer on the flight deck "in command" was the critical hole in the cheese (in combination with the CRM deficiencies that precluded the PM from assuming control).