And I, as a Man United fan, think that it will be a big loss if Man United releases Garnacho to Napoli. He is one of Man United's wonderkids, his potential is very large, so Garnacho is very worthy of being maintained by Man United.
Maybe the coach is just trying to make Garnacho understand that he is not indispensable from the team so that he can put in more effort to become better because once a player starts thinking that they are untouchable in a team, the chance of their performance to reduces increases then. Some of these players need a wake up call and if he doesn't move in this window before it expires it will be a wake up call for him to really put in more effort to impress the new coach so as to maintain the first team selection.