Well I was in the sim recently for a six monthly LPC, and we actually tried the same. If you try to disconnect the A/Th. (by depressing either instinctive pushbuttons), while in the Alpha Floor protection range, it will re-deploy Alpha Floor mode immediately, in real time. This is because, as Human Factor said, Alpha Floor and Alpha Prot mutually exclusive protections. The best thing (I would say the ONLY thing, as well as Airbus Industrie would, say) to do should you have an Alpha Floor situation triggered off. Would be to decrease the angle of attack (Alpha) as much as possible, and once the TOGA Lock is displayed on the ECAM, to disconnect the Alpha Floor as per procedure.
What I'm trying to say is that the Alpha Floor protection is exactly what it's called..... a 'PROTECTION' !! Therefore, as long as the aircraft computers think you need it.... USE IT !! once you dont need it any longer, and the aircraft tells you the same, and YOU as handling pilot (with the CM1's approval in case of CM2) feel you do not need TOGA power any longer, disconnect it by all means.
Any of the protections below Vls are paramount to the safety of the flight, and should as such be given their due importance.