to be honest he doesn't have to justify it................he's free to do what he likes with his carreer, if he feels he still wants to fight then its down to him, many fighters in worse poss have got back into the ring ( joe messi, tom morrison etc etc) so as long as he's got a clean bill of health, ok upstairs and can win the odd fight

having said that i felt he may have retired after 20 defences, i'd like him to retire so his legacy doesn't get damaged