About stance width...it seems to me that one huge defining thing is whether the stance is wide with the center of mass held between the feet, or if the stance is allowed to vary and the center of mass moved dynamically inside the turn and both feet outside the CoM.
About femur rotation...PMTS does not rotate the femurs to steer the skis. Of course there will be some rotation when the body moves, but as E said, no intent to rotate. Why not steer? For me, the difference is whether the arthritis in my knees lets me ski at all or not. Rotation puts a stress on my knees that hurts. No rotary movements transferred through my knees lets me ski all day with great fun.
I think it would be fair to say he has rotated his outside femur inwards in his hip socket. That has increased inward flexion on his knee and applied increased load to the tip of his outside ski. I do not view this as a passive muscular movement but quite active and intentional. At the same time he is rotating his inside knee inward (inward flexion) and though his hips are fairly square to the turn this must also create outward rotation of the femur in his left hip socket. Again a very active muscle movement. In neither case does the rotary forces he creates (regardless of the origin of the movement or force) results in a carved turn, not steered. Why? Because his skis are on edge, not flat. Perhaps the rotation of femur in the hip socket is an implied action in high level skiing and needn't be discussed if all other mechanics are in place, sort of like stance width but I'm not so sure.
Thanks again for clarifying.