He's already considered the greatest player ever. I don't really think winning titles as an owner will mean anything to his legacy.
It will definitely cement his legacy as the greatest player ev...oh wait. It will definitely cement his legacy as the most influential...oh wait. I guess it will mean he will be the best player/owner...oh, he's the only one? Well, I guess since he is arguably the greatest, most popular player in league history there isn't much he do to help improve his legacy at this point.