I totally agree that Ashley and Llambias are to blame. But how can you say that the twitter posts had nothing to do with it?
We have a clear line of cause and effect - the club (therefore A & L) offered him a deal, he wanted to negotiate, they wouldn't (fine in my opinion), he mouthed off (continuously, starting from before the contract offer) on twitter, the contract was withdrawn.
How would your boss react if he offered you an extension of your contract and then you told EVERYONE, very loudly, that he didn't know what he was doing? Would you expect him to offer you a longer contract? More money? Or would he tell you to piss off?
Personally, if Ashley had caved I would have called him a soft-as-clarts mug. And he would have had no power at all to negotiate with the players. Now, he is getting called a ****er for sticking to his guns and letting Barton leave. But i'm saying well played Ashley - you've shown Barton (and the other players) who runs the club - and it isn't them.