[Yoda]

And herein lies the paradox I've been trying to solve. If the Vertical Wristcock Motion occurs on the Inclined Plane, lets say the Turned Shoulder Plane, this means the entire Left Arm Wedge is also On Plane. But this cannot be the case since the Right Shoulder defines the Turned Shoulder Plane. What am I missing here?

The palm of the Left Hand does not lie in the plane of the Left Arm when the Left Wrist is Flat (upper Left Arm in line with the back of the Left Hand). Because of the heel of the Hand, it is sloped away from it (counterclockwise) and appears 'more vertical' at the Top (and In Line with the Plane of the Turned Right Shoulder). Thus, the Wrist can Cock on Plane without the Left Arm being On Plane.

Maybe what you are considering the Vertical Wristcock Motion of a Flat Left Wrist is really the Vertical Wristcock of an Arched Left Wrist (which puts the palm in line with the lower part of the Left Forearm and therefore not On Plane with the Right Shoulder).