And the point of possible/probable recovery will have been long passed at that stage.
From 35,000ft there's quite a lot of time to try things. In AF447 at the time the Captain returned to the cockpit the stall warning had either already stopped sounding or stopped a few seconds after, so I don't think he suspected a stall at first:
At around 2 h 11 min 42, the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped...