The guy isn't going to be hired as a DC ever again. He should easily have enough money to live VERY comfortably without ever working again. Even if the Saints did implement a pay-for-injury program (which I'm about 95% sure that they didn't), he'd be smarter not showing up.
So if the NFL caves in to Williams demands, that would mean Williams suspension would be shorter then Payton's. Without Williams, there is no pay for performance system. Its complete bull shite if the NFL gives in.