The triangle and attitude of arms is consistent with GOAT position. He starts his arms there and maintains it throughout the swing. With a the exception at the top of a Full swing.
His commitment to keeping left arm straight may be the cause of his odd looking swing.
His rotation concepts agree with TPL, Cheney and Shaw.
Basics - start with chipping
Lead arm - Keep straight (except for a brief moment in driver back swing) This is his key end range. Club head stays ball side of hands. Stable hips (for chipping) Handle stays in front of chest points to handle (except for a brief moment in driver back swing) Trail arm is straightening through the ground. Push the ball down the line with the Trail Arm (this is very much a trail arm feel) Basics - part II
Center of gravity COG get to left hand side, get center of gravity to left hand side COG Get weight to lead side (1:30) Stay forward on lead side Lower body rotation Posting up (5:00) Sequencing tips
Sequencing tip, put alignment stick through loops in belt - arms should never touch the stick, arms should just fall in first part of swing (4:20) Stand tall through the swing… (9:51) This is why he wants all clubs the same length. So he can always stand tall.