sure. but fighting is a mental game to a large extent too and if you've given most of your adult career to it its just not in your blood to stop testing yourself.
I dont think anything could be done to damage Roys legacy, he did what he did in his prime and thats what makes him a legend. He keeps fighting because he loves it. Holyfield, despite recent money issues, would do the same otherwise. They love the sport, fighting is all they want to do, but its they're prime we'll remember as they're true selves. Roberto Duran went on far too long, I mean sure he beat barkley in what should have been the latter stages in his career, but he continued to fight long after that. Doesnt change his standing at all, with regards to all time greats. we dont remember him soley for no mas either, we remember him for his work as a great lightwieght and beyond. with roy we'll always remember him for what he did, not what he's doing.
Fighting on too long and when you're a shell of your former self just messes with fans' last memories of the fighter. It really doesn't detract from their legacy. Or if it does, it's minimal. It's the norm in boxing for greats to fight on too long.
Best example is Jones, but Joe will be next. Joe loves the boxing, but the pressure of the fans is going to make him keep coming back until he gets KO'ed or beaten and then the fans will be all over him of why he did not hang them up much earlier. Joe is 36, but fights like he is still 26. He can get old the very next fight. Ala SRL, Norris, Duran, and the great Ali who did not have to fight Berbick or Holmes. Fathertime is the worse enemy of a fighter.