Surely this is the crux of it, that’s two managers now who have seen him in training, and admittedly limited minutes in games. Both have decided not to integrate him into the first XI!
I think going to somewhere like Sheff Utd would be his chance to prove he has a future at the club, do well, come back and be a serious squad player, although I understand what you are saying about auto-write-off of players, but I am not negative by default and supported Jannik well after he had been written off, even Bouba although that feels like I just plain go it wrong. If they play for us, they get supported, just seems Tom has not shown enough in training across multiple managers.