Hi mm43,
As pointed out earlier, the clockwise heading change is greatest when the Ny driven oscillation is dampened by hard over and held left SS inputs.
I think the clockwise heading change was due to adverse aileron drag when the wing was stalled. The differential spoilers would have been ineffective in the turbulent flow above the wing. But the RH down going aileron would present more drag to the forward aircraft direction and induce a turn to the right, effectively "the wrong way".
I think that was first explained by Owain.
edit:
So my feeling is that the PF managed to dampen the Ny oscillations that could have easily resulted in a total LOC.
I don't think PF managed to do anything other than mostly pull back during the stall. His roll commands were ineffective once the wing was stalled.