See if there is a bicycling class offered by the League of American Bicyclists in your area (they are "in the middle of nowhere") and make him take it.

He may have a right to the road, but he doesn't have the right to be an self-centered azzhole and to put his life in danger and his family in a position where they (you) could quite conceivably have to deal with tragedy. Maybe you should tell him that.

The trauma nurse idea is a great one. Or make him volunteer in a brain injury clinic or workshop.