...at the age of 57.
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Actually, IMO it's much more reasonable to take up risky hobby's late in life. Only real issue is your reflexes are slower and your recovery times are longer, but I don't see either of those being an issue for this kind of stunt.
In highly technical sports like MMA, the knowledge and muscle memory must be a pretty big advantage, but unlike this stunt, reflexes and recovery times are very much at issue. :-)
Or getting the next weight category title... (he said that on his age defending middleweight title was getting harder, as he was getting too old to do violent weight shifting, and was considering just fighting without weight shifting...)