I think we may be mixing stuff up a little here. The Right Forearm and Clubshaft should be IN THE SAME PLANE to maintain the Right Forearm Flying Wedge alignment . . . . but only on the INCLINED PLANE when the Right Elbow is On-Plane (I think?).
MOTION All the action of the Golf Club takes place on a flat, inflexible, Inclined Plane, which extends well beyond the circumference of the stroke – in every direction. The full length of the Clubshaft remains unwaveringly on the face of this Inclined Plane – Waggle to Follow-through.