My advice to him would be…
Take off a couple of months with no golf. Come back. Hit nothing but pitches for a week.
Week two, hit nothing but pull fade 7-irons from an extreme forward ball position.
Go play every day for 7 days where every shot, including tee balls, is a 9 window shot. Rotate them.
Then play 4 consecutive weeks on the PGA tour.
He needs to level out his shoulder turn, but he needs to dump all internal cues and just get back to shot making. Week two will work on the major mechanical issue without him thinking mechanics.
9 window being upper left for a high fade?
What is a 9 window shot?
I believe it to be in order to left to bottom right;
High Fade | High Straight | High Draw
Mid Fade | Mid Straight | Mid Draw
Low Fade | Low Straight | Low Draw
What would the 7-iron fades from an extreme forward ball position do?
Level out his shoulder turn and move his path left.