The aircraft may have entered a stall at altitude, but it is not reasonable to assume it was still in a stall when it impacted. The airspeed was too high.
Something else prevented the PF from leveling the wings and pulling to the nearest horizon.
Was it an instrument problem caused by unusual attitudes, or was it a case of massive crew disorientation?
The spiral dive indicates that g was available but that the lift vector was pointed in the wrong direction.
From the BEA note on the flight recorder readout:
The aeroplane then turned left and quickly lost altitude, with large changes in pitch and bank. The rotation to the left continued until the end of the recording. The last recorded point, 1h47mn15s, corresponds to an altitude of 1,600ft, a speed of about 380 kt and an extremely high descent speed.