Didn't they suspend him indefinitely from team activities? Given what happened with Hunt after they cut him and we signed him and barely took any shit for it, I think they wanted to avoid a repeat incident. Better to keep him on the roster, suspend him, and hope this shit blows over (which it probably will as soon as another NFL player does something terrible...only a matter of time) than to cut him and let him end up somewhere else on a bargain while that team shoulders a fraction of the outrage.
Plus, there's not a lot of downside for them here. They can sit back and let the investigation run its course. It sounds like his wife is willing to take the fall for him, which means he'll probably still be an NFL player, although he will probably be suspended for a time.