I agree, Lagster that the fear of banging the ball to the right does cause a lost of Lag, but IMHO, as an outcome of the subconscious result of STEERING. I also think that a fear of totally missing the ball leads to a Lost of Lag due to throw-away- a form of Steering. These golfers just swing the clubhead instead of Educating the Hands.
As you posted, the Hands need to go thru the Line of Sight (centered head) before impact. I do agree that golfers ‘see’ the clubface “open” without the knowledge or know-how as to how it “closes” and quickly try to adjust. The Rhythm of a Flat Level Left Wrist thru the Line of Sight will prevent Lag loss. Here, as your lesson accomplishes, the pivot should respond to the Hands as they Roll on the Straight Plane Line.
How about a fundamental misunderstanding of angular motion and thus why the club is hook faced?