Valpha prot is the AOA threshold from where the side stick will command AOA directly instead of load factor demand. Valpha max is the maximum AOA that flight control computers will let the side stick achieve and/or hold. With AP is off and side stick neutral if the aircraft is pitched up beyond Valpha prot due to disturbance it will try to pitch down to Valpha prot and not pitch up to alpha Max. If the pitch up is rapid then Phase advance will bring this threshold to a lesser value. The effect of activation of this protection mode is that trim freezes at entree point and the aircraft will stabilize at that AOA when stick free, But Pilot's action in A340 case would be same push forward to stop climb and that would bring flight controls out of protection mode to load factor demand which was not done and instead attempt was made to engage AP which does not engage when in protection. So this incident is not attributable to FBW characteristic.