The England international was said to be on the transfer-list this summer, though United are now insisting he is not for sale.
Brown told Football Insider: "There are a number of players Man United want to get rid of. From what I understand, Kobbie Mainoo is not one of them after a change of mind.
“The likes of Garnacho, Sancho and the others who have been left out of training in pre-season, that’s who the club are looking to raise money from.
“In my opinion, they should never have been considering letting Kobbie Mainoo go, it was a crazy idea. After he didn’t sign that new contract, it looked like he had decided he wanted to leave.
“That interest didn’t really come as heavily as they maybe expected, but I won’t complain about that.
“From what I hear, he’s going to be happy to stay into the new season and hopes he’ll be a bigger part of the team as Amorim is going to use him more regularly.“