It's not coming from a place of hate. Ultimately, it's coming from a place of doing better business. Assuming Sancho is on 200k a week and is as insubordinate as we've been told, he would also be desperate to get out of the club. If Dortmund can only pay him 100k a week (assuming hypothetical figures here), why should he earn the entire Man United wage if he doesn't want to stay and fight for his place here. And that is how this situation is similar to Joao Felix. The player wanted to leave and was desperate to play there. So Atletico told him that they wouldn't pay him a single penny and he's getting what he's getting from Barca.
If the club subsidizes his wages, there's no guarantee that it'll be good business for the club in the long term. Look at our previous loaned out players. We got nothing for Sanchez, nothing for Bailly, nothing for Van De Beek (when at Everton) and nothing for Martial. The players who aren't cutting it out for us should not be getting their full United wages if the clubs who loan them aren't going to pay it. If they want to sit around and let their careers stall, so be it. Ultimately it would come down to the player and I'm quite sure that the player would bend.