I considered this at the time, but I also decided not to dig at it. Z is still around, but I imagine Z would protest when I suggest that the summary of the punching incident was a throw-away line of "I'm too crazy for treatment".

If the inquirer took the bait, they would end up arguing about a specific incident that may or may not have gone quite like that and may or may not have had motivations that actually make in the bigger picture. (i.e. ongoing arguments, several-directional fights) Setting that down, and not delving into it, was me maintaining composure and actually having the rest of the conversation.