I would really work on trying to get to hunt with him and his partner, my dad is 70 and still comes up to hunt every year with me and 2 of my 3 kids, one of my daughters tried it and didn' t like the waiting part.
Yes I do all the work,scouting, setting up stands,dragging,skinning etc... But to have three generations hunting together and telling stories and talking family history for one week a year is definatly worth the work!
Try to sell them on the tradition of the hunt as well as having young legs around to do the tough stuff.
It is sad to think that he left one to rot, but get over that one and try to help them out next year!