I'm just going off from you said in your earlier post about Mourinho having to play with two strikers, as he doesn't have the number 9 to play a sole striker.
Look, I don't know what systems Mourinho has in mind for the new season. It maybe the case he will play one striker in the bigger games and two strikers in the lesser games. But even by shere numbers, we would have to replace Zlatan and an aging Rooney.
Belotti looks a real good player. And how does any team, especially United, buy a "bench" player? Surely, we buy the best players available. Some players would want guarantees of a starting place and some would be happy to come from a team like Torino and do their upmost to be in the first team of a massive, once in a life time club, like United.