Fandangled,
I have never flown an Airbus, but can answer your question. The various protections offered by the flight control system require the computers and sensors to all be working normally.
When the computers are working normally, the system will be in "normal law". It is in this mode that all the protections work.
In the case of this accident however, because of errors in the airspeed sensing, the flight control logic had dropped back to "alternate law". Stall protection is not available in alternate law.