Remains the question of the use of his SP. About chopping is no doubt he masters the movement, but and about the attacks?
He could use many other type of inverted to FH chop, adding some more backspin when chopping, twiddling, serving or even for some small loops.
I observed no blocks (right or left) or flat hits with the ball asking for it. Ok, we are talking about videos where he plays finals and is better play a safe game.
In all, what I pretend to express is: if is not to use the SP in an agressive way what's the point? This question is more important when in other side is an anti (or LP)....
SP has some important advantages for a player at his age. It takes much less energy to use than inverted does; being less powerful than a younger man, he needs this. And SP is much safer to hit with. As he is using his anti in part to disrupt the opponent's play, he may expect high balls (pop-ups) - smashing those with inverted is far harder and riskier.
I think his choice of rubbers is very practical and demonstrates a great insight in the game.