The only thing that springs to mind about this is simply MONEY. Barton is a money sniffing ♥♥♥♥♥ like too many of the rest of them. He's simply spat his dummy out because Newcastle were not prepared to offer him a 4 year contract.
He then proceeds to make his mouth go in public after the club has supported him during his prison time and lenghty injury. He's a thick plank who's yet again paid too much money with little grasp of reality.