DW
Or, y'know, ask.
("Are you pulling up?"
"Yes. Shouldn't I be?"
"No - we're approaching stall - I have control."
"You have control.")
An exchange for which there was plenty of time between disconnect and apogee/stall.
Why shold he ask? What would have triggered him? Why should one assume, that the PF is applying backstick in a situation, where it is not appropriate? Even the aircraft talked different to him after the initial pull. From 02:10:29 until 02:10:45 and from 0211:05 until 02:12:00 the loading was below 1g, thats more than 1 minute less than one g against 26 seconds with g at max 1.15. The instruments should have triggered him, absolutely correct. But he didnīt get the clue, otherwise he would have asked or even he would have taken over the aircraft like you mentioned, correct? Maybe he was thinking some kind of updraft, some kind of misreading altitude (speed was gone, why shouldnīt VS and altitude not be affected)? Maybe the unloading gave him the impression, that PF is doing the right thing.
We donīt know what he was thinking, what he was "guessing". But he couldnīt see the SS input and he didnīt ask, and he didnīt get to the right decision, that one we do know.