Sounds like he was tough, but also he was being looked after.
He tried to do the right things, was experienced, in shape, had survival supplies (bad luck to lose the backpack) and seemed to know what he was doing.
Too bad he's giving up doing these adventures, instead of getting back on that horse. I'm sure he's got a good set of lessons learned. I bet he would also keep a good quality life vest on complete with essential survival items, so that he's not separated from them. When I used to kayak a lot I used to keep essential items in my vest: stainless steel knife clipped to the outside for ready access, firestarter kit (2 lighters, BSA Hot Spark ferro rod, pjcb, & fatwood), mini trauma kit, compass, signal mirror, safety pins, foil, water treatment tabs, etc. Always with me and never touched. Kept a more complete kit in the boat.