He needs to go or else he will be warming the bench. We signed 3 upfront players and with Zirkjee on the bench as well, its pretty clear that he wont be getting any play time. I personally think that he is a decent young player but currently Manchester United doesnt have any privilleges to nurture young players because we need better players right now to help us get back to top 4
Its pretty much the same case with Garnacho as well, if he stays on the club then he will most likely stay on the bench hence that they need to move out to another club
Sending Hodjlund on loan to Napoli is the best thing for his career he's a young player with lots of talent and if he continues to stay at the bench he might totally lose his form and fail to improve but at Napoli he'll get better playing time and improve in a better environment where the current issues of the team won't affect him.