It sounds like the situation was very 'run of the mill' as it started. Just an unresponsive passenger that they were going to offload for medical reasons. I don't imagine that the pilot was anticipating any threat, and was only there to help explain why the individual could not fly.

Sure, if he's being rowdy or assaulting crew on the way back...stay in the cockpit. But just to explain a situation? I think the pilot just got some bad luck. And I hope he recovers quickly to watch those two enjoy a decade behind bars.