It is actually not a bad decision to actually let him go for that amount or even to loan him out. First of all, he has high weekly wage and it looks like he is going to stay on the bench for most of the time next season so I dont see why should we keep him in the team only for him to be a bench warmer. Aside from that, everyone knows how bad he is therefore there is no reason to actually keep him in the team
Harry Maguire did not have good games on the field last season, his mistakes were always in the highlight, and he had a suicide goal that was quite burdensome for the team, the price was fairly expensive with unstable performance. If in bandrol at a low price is a natural thing at this time, or lent it may be better than being maintained with such conditions, even though you have to swallow losses.
On the other hand financially is difficult, but the team needs to take action that should provide benefits to the team from its performance, I think this decision is the right decision rather than providing blind salary to him.