This piece of information may well be buried somewhere in this thread, but just where did the pilot get the idea that repeated and full deflection of the rudder would correct any apparent or real upset caused by wake vortex? If it was from AA training dept. then you have to wonder who dreamed up such a scheme in the first place.
If you encounter an unexpected skid situation in your car, perhaps caused by icy conditions and worn tread of the tyres, do you repeatedly apply full steering inputs, first in one direction and then in the other, or do you apply slight and gentle inputs in the direction of the skid?
I know which action is likely to lead my safe recovery and which is liable to end up wrapped around a tree some way off the road.
The pilot was either badly trained, misinformed or plain silly. Either way, he was the major contributor to the accident.
The ice and the tyres contributed to the initial event but did not cause the subsequent crash.