Why not? It's still very unprofessional to state publicly wanting to leave a club because you're just after a new contract. Different scenarios yes but Di Maria to my knowledge hasn't made anything public, only quotes I've seen during Copa America is that he wants to fight at United etc.
We can have all the money in the world but it means little when we can't sign players who are unavailable at this time.
I want him because he's a world-class player, pretty simple really, we only have a few and any team would look worse without him. Even at his worse by his standards last season got the most assists in the team. He can unlock defences with passes that no one else would even be capable of. It's always good to have a player who can create things from nothing even when playing poorly, he did it at times to get us crucial goals, people forget how good Di Maria was in first few months as well. Not at his best but still started off very well. Has a history of starting at clubs slow, always want to have at least another season from him.
IIRC club played their role nicely by leaking stuff and pressuring Rooney to sign new contract. At least he buckled down and offered a lot after the saga.
On the other hand, Di Maria might not have said anything in public but he has already agreed contract with PSG and forced Manutd to sell him. He even refused to join the squad which is Raheem Sterlingesque.