The THS (and for that matter elevators, ailerons etc) are not prescribed movement limits in real-time (which would be inefficient and unnecessarily complex), they are set to follow the commanded flightpath, whatever that may be.
You are misinformed
Dozy.
Reaching alpha prot, the THS just stops moving.
Anything above alpha prot is done on the elevators only.
It is not 'inefficient and unnecessarily complex' it is commun sense.