"in two minutes we should enter an area where it’ll move about a bit more than at the moment, you should watch out" and he added "I’ll call you back as soon as we’re out of it".
They were clearly expecting some "buffeting", so isn't it likely that any stall buffeting they felt, when combined with a "what's it doing now" a/c that seemed to be seriously misbehaving, would have been missed, or misinterpreted?
I was once the best damned VW Beetle mechanic I knew... but then I got one that was fuel injected and it had a computer, and lots of sensors.... whenever anything went wrong with that thing I almost always thought it was the computer fouling things up... and it rarely was.... I was almost useless with that machine.
...point being, I think it's entirely possible that the PF was under the illusion that, since his airspeed was u/s, and other things didn't seem to add up -- how come when I pull back on the stick I don't feel my body being shoved into the seat? -- the PF said "I don’t have any more indications", and the PNF said "we have no valid indications"..... the "what's it doing now" airplane must be badly fouled...
Given the 30 seconds of aft, left stick he'd held at one point, it would certainly seem he must have been acutely aware of some kind of an apparent disconnect between his actions and the ship's response.