You are both entitled to your point of view, but as of yet I haven't seen any evidence supporting this conclusion having watched him play similar midfield roles both for Manchester United and Scotland. I am open to reconsidering that point of view if you wish to point me in the direction of some convincing evidence - otherwise I am content to maintain my own judgement on this topic.
I mean, just watch him when he plays.
Statistically, he consistently gets on the ball about 20% less than any of our other midfielders. Last season he averaged 59 touches of the ball a game, which put him in the 46th percentile for central midfielders in Europe's top five leagues. A Man Utd central midfielder is in the bottom half in his position for how much he touches the ball. To put that in context, Fred and Pogba were around the 78th percentile, with Matic in the 90th. Even if we go back to the previous season when we played much better, Scott was still only in the 59th percentile, compared to the 83rd, 81st and 94th respectively for the other three.
The video you talked about (which I'll post here for you) unfortunately doesn't show any actual examples of it happening, but from memory does explain well what he tends to do.
I wish I could remember what match it was (I think it was late 20/21 but may have been early last season) which had the most perfect example of it I've ever seen. I'd love to go back and clip it out just to have something to show what I'm talking about. The ball started of with Shaw on the left. McTominay was the closest midfielder, but he was standing behind an opposition player who was cutting off the passing angles. Shaw passed it inside to Maguire, and as that opposition player moved across Scott continued behind him. Maguire passed it to Lindelof, and both Scott and the opposition player jogged across the field. Lindelof then passed it to AWB, and that opposition player then moved forward to cut off a different passing angle...so Scott instantly then jogged over and stood behind a different opposition player. A good 30 seconds or so of play, going through four different players across the entire width of the field, and our central midfielder spent the entire time taking himself out of the game so the defenders couldn't pass it to him. It was absolutely amazing, and if I didn't already shave my head I swear I would have been pulling my hair out in frustration.
He does have some matches where he actually makes himself available and looks to get on the ball quite well. Not often and it's certainly not his 'normal', but it does happen. That is both the most annoying thing (if he does it occasionally why doesn't he do it all the time?) and the thing that gives some hope that he can be trained to do it all the time.