[Yoda]

...if there was a true magic right arm thrust down the line of the left arm tether then the left wrist would have no cock at address and wouldn't cock at all during the backswing.

...What we are feeling on the backswing is the triceps developing a force that prevents the elbow from bending too quickly and/or too much.

...True extensor action down the line of the left arm can only occur when the left wrist is uncocked.

Using Pressure Point #3 (Right Hand Forefinger) to stretch the Left Arm and simultaneously pull the Clubshaft into line with it does indeed inhibit the Left Wrist Cock. However, using Pressure Point #1 (the heel of the Right Hand against the Left Hand thumb) to stretch the Left Arm only does not.

As you have noted, the Right Triceps Extensor Action -- by definition the 'steady effort to straighten the bent Right Arm' (6-B-1-D) -- does indeed prevent the elbow from "bending too quickly and/or too much."