That is the mysterious part about it: why would they let it get into a fully developped stall. In an Aircraft of the momentum and mass of the A330 going from normal flight via incipeint stall to fully developped stall is unlikely to happen in a fracture of a second.
At least in straight and level flight this process takes time.
And leaves time to react.
Theres another scenario to consider then isn't there, that the aircraft was turning, perhaps they considered the best way out of a storm cell that they didn't know was there is the way they came in, a turning aircraft with the handling pilot trying to reduce speed that appears not to be whilst the aircraft is descending due to downdrafts may have been attempting to trade off speed to maintain some height, only speed is not reducing, with thrust at idle, nose attitude high, severe turbulence, and bank angle,(perhaps exaggerated by turbulence) how long to stall now?