I believe all of the backlash regarding the pictures really did him in.
Remember, he didn't get the immediate backlash following the alleged domestic violence allegations, that was all focused on Hardy. He came back and he was just trying to be Greg Hardy with the comments regarding Brady's wife and there was backlash, follow that with the pics and then the twitter nonsense probably made him feel real easy. I don't think he understood just how big the spotlight is on this team compared to Carolina when he signed. If he resigned with Carolina, those pics probably don't even hit the press.
Rumors are once those pics were released, that tardiness followed so it makes sense that all the backlash weighed in on him.