He was arrested, and therefore surely unable to fulfill his contractual obligations. Of being available to play for the club. Which I would imagine is different for arrest or conduct than for injury etc.
I'm sure when the club decided not to pay him, they would have known where they stood whichever way the verdict went.
By the same logic of him suing the club, the club could sue him for loss of transfer value, for example.
It is a band move from him, but at the same time, he will be taking advice, and somebody somewhere will think he has a case.
I am fine with however this plays out, it is a matter of law and how people that deal with it apply it. I think the club probably did the only thing they could have done.