I'm not an expert but I play my best golf when I have the extensor action you describe combined with the "Magic of The Right Fore Arm".
Refer to 2-F and 7-3
"In essence, bending and straightening the Right Elbow will raise and lower the left arm and/or cock and uncock the left wrist without bending, flattening, or cocking the right wrist. Right elbow action either powers and/or controls all three elements of the Three Dimensional Impact, (downward, outward, and forward)." Homer Kelley
Regards