Who knows? That is the point, we all so desperate to hate him we seem to think him wanting to leave can only be cos he's a rat. I don;'t believe it is that simple.
No, he's a rat because he wants to get off after running down his contract at the club that made him what he is.
What reasons do you have to believe that it is something else other than what's been said? Are you going to wait for Barkley himself to come out and explain why he's getting off?
He's had all summer to do that and was more arsed about telling us all that he didn't do that medical.