Just started an A320 rating and came across this today incidently. My take on the subject is that there would've been an unprecedented amount of turbulence or similar for the a/c to be forced out of pitch/bank/speed limits and thus the a/c would very quickly find itself in a situation which Normal Law should've protected against, i.e. Abnormal Law. It would've been sensed that flight controls were not responsible for the upset and therefore it would be wise to assume that the general area in which the a/c is flying in could result in the same thing happening again. Therefore Airbus made the decision to not afford any protections in this situation as these protections against external forces could overstress the aircraft.