FO's stick was full back for most of the event.
A confusion factor might have create into the event when the stall warning stopped due to excessive AOA. Forward stick was applied which reduced the AOA into the normal (expected) envelope which re triggered the stall warning.
Perhaps aerobatic experience with zero G, and an unloaded wing and very low, or no airspeed, might have helped in analyzing the situation and made someone realize zero G was their friend.