Edit: regarding the pilot who did the wrong thing, I don't think it's fair to say that he didn't know how to recover, either. He almost certainly knew how to recognize and recover from a stall. He was a glider pilot, where stalls are a matter of course. It seems that he panicked, which prevented him from thinking clearly and taking the proper actions. People do that sometimes, and a big reason you have two pilots is so the other one can step in when one of them gets stupid. The fatal flaw with the Airbus was the system which failed to adequately inform the other pilot of the first pilot's stupid actions. (In any sensibly designed aircraft, the two sets of controls will move together, providing physical feedback of each pilot's inputs to the other pilot.)

In addition to the warning light there is an audio warning "DUAL INPUT" and tactile feedback (stick vibration). The fact that the pilots did not recognize this condition feeds into my point about them not flying the plane nearly often enough to actually understand how it behaves in anything other than an ideal condition.