By the time Captain Dubois arrived on the flight deck, the situation had progressed to the point that the aircraft was not properly following the controls. Both the copilots loudly made exclamations that the aircraft was not under control. In effect, he had walked into a cockpit full of wasps. Apparently nothing in his background had prepared him for unraveling such a mess.
And there is no certainty that even the SW was still on at the moment of his instrument scan.
And of course nobody want even to try to establish if at that time a determined (or yes, desperately) maneuver would allow recovery (no, not only full fwd stick , but rather a forced direct law + manual trim full ND at structural limit, even if that would made things to fly in the cabin, followed by a recovery at the g limit again).
After all many "impossible" situations were saved by pilots performing unstandard and untrained maneuvers. But yes - in a good situational awareness, which was not the case of AF447 - this plane set trap after trap to his crew, and of course they are only to be blamed for falling in ...