Wouldn't that be cured by turning more? Usually the hands have to make up ground when the shoulder turn is lacking.I think he is a little, but in a good way. He is just staying in bat lag longer. Too many arm bar hitters exhibit one of two things. Either their wrists start to snap prematurely, or they reach full, or near full extension prematurely. typically with the arms extended toward right-center field when pulling the ball. This is because the barred arm over-extends the right forearm rather than maintaining the "power-box" as in the first 3 photos of the girls. The 4th photo shows Peter Alonzo and perfect form launching the hardest hit ball I ever saw and his power-box. In the last 2 photos the batters are able to get their hands inside because they DO NOT have arm bar, there is enough flex maintained to get the hands in, out front, and maintaining that perpendicular relationship to the bat and driving through contact.
In the video his arm is not barred. It is bent enough to even allow more flex on an inside pitch to get the ball on the sweet-spot and keep it fair.
Also, what's wrong with full extension if there's a lot of bat speed?
For a set rotational speed, a longer radius means more barrel speed, so having the hands extended out from the center of rotation would be a good thing.