The FA should have said enough is enough and slapped a life ban on the guy. The kick at Aguero, after he had been sent off, was utterly beyond the pale in itself, but Barton then compounded the crime by claiming on Twatter that he was deliberately trying to get a Man City player to retaliate in the hope of provoking a red card to "balance" things up. We talk of "professional fouls" but this has taken the unacceptable face of "professionalism" to a new all time low level.
The guy behaves like an animal when he loses his rag and he constitutes a danger to other players. There must be a screw loose somewhere because he is such a Jekyll and Hyde character, sometimes sounding intelligent and decent, and then returning to ugly type when something flips his switch.
Ban him for life is the only answer. The FA have bottled it so QPR should sack him and every other club should agree not to sign him.