My uneducated guess sees this scenario.
They reach out to his agent asking if he's interested,
Agent tells them he'd listen to what they have to say
Man united comeback telling him they will give him a massive pay rise
Halls agent says go on then
Man united put feelers out to us
We tell them a price they aren't going to get near
They leak this 50m fee and the interest to the press
Crickets
They walk it back.