I went back to him with the head before finishing The Naked Truth, and when he heard of the situation in the mines he simply didn't want the head anymore. Can't remember what he actually said, but that seemed to be the end of the questline.
I also couldn't finish The Naked Truth. The quest seemed done, Nadia exposed him and the miners are standing there screaming at him. But nothing more happens and the quest is stuck in my log.
