I don't agree. Hindsight is 20/20. The issue facing the captain when he came to the flight deck was simply who was in the best position to fly the plane. That's a judgement call, and a bit of a coin flip. To me, it says that he trusted in the professionalism of his fellow pilots. In hindsight, that judgement may have been wrong. But I won't second guess that decision.
It's like his decision to take his rest break when he did. In hindsight, maybe it wasn't the safest course of action. But he had no more of a crystal ball than anyone else on that flight.
I think there is a temptation to expect the captain to ride on his white steed from the bunk onto the flight deck, manfully throw the stupid PF out the door, and heroically wrestle the plane to safety. That would make for a thrilling movie plot but it doesn't reflect the way CRM actually works.
This is not about the Captain taking control. It is inconceivable that the Captain did not seek to form a view of what was going on. The question then becomes why, given that he was not present for whatever cues led the other pilots originally to misinterpret the situation, he nevertheless joined in that misinterpretation.
Usually when a non-participant acquiesces in, whilst not sharing, an erroneous view, the non-participant is junior to the actor(s). That is not the case here. Assuming the Captain wasn't erroneously briefed by one of his colleagues, then the natural conclusion is that the Captain
independently came to the same conclusion as the other pilots or, at the very least considered that no alternative explanation was sufficiently likely so as to distract other pilots by raising it.
It seems to me the likeliest explanation is that the aircraft was still giving some powerful cues consistent with the erroneous interpretation. They must have been powerful cues because three men did not interpret a stall warning as meaning that the aircraft was about to enter a stall.