On its face, the NU prior to STALL WARN is consistent with what Machinbird describes, and it is consistent with a Training failure and the PF's preoccupation with overspeed. Because it is prior to, PF had other indications that she needed not to be low in the NOSE?
If the warning is due increased speed into the realm of STALL WARN proper function, and not its disapearance at arbitrary "low" speed, the a/c is accelerating, and likely because the NOSE is dropping.
We've been there, but w/o the dropping nose. Inappropriate 'Approach to STALL training', and the PF's obsession with overspeed. No one it seems, including the Captain and LHS, wanted this bird to drop her nose and fly. From the stubborn reluctance of Bonin at first, and the pleas of LHS, to this NU at STALL WARN (!), to "Climb, Climb..." "No, don't climb..." "Pull, Pull, PULL..."
Complete unfamiliarity with a tail low STALL? Fear of overspeed? Could it be she became completely uncontrollable as she approached level flight? What would cause that? Was fear of airstream noise and its implications the driver instead of the crew?
Because if the single unknown factor that caused this wreck is the hidden RHSS, someone has some splainin' to do.