The Glazers are not selling the club until the end of next season when they intend to get a higher bidder but it looks unlikely based on Manchester United's performance. The club needs to be patient with Erik Ten Hag because it might be too early to let him go. Nobody stopped Harry Maguire from leaving the club this season, the issue was that there was no serious club bidding for him. He was told to leave if he got a club, so he should already know that he would spend more time on the bench. He is free to leave the club anytime he wants because I don't think he is part of the coach's plan.
This is what makes the Glazer family hated by most fans of United because they are considered to only want business without caring about the condition of the club. But indeed it can be realized and what the fans say is true but on the other hand the Glazer family is also a businessman so they will still wait until they are absolutely sure that the offers of some people who are currently happening such as Sheikh Jassim who currently seems still very strong and has approached will be a little hassle with the selfishness of the Glazers who do not let him control Manchester United.
For Maguire, he could have left Manchester United last season but of course we know that the offer was flatly rejected even though West Ham had previously raised the offer several times but it was considered not according to value even though the price was quite good for a Maguire.