I was also a national Tae Kwon Do champion in my teens, just not in America. America isn't known for it's Tae Kwon Do. So on that, we are even.
However, that's irrelevant to the argument of whether you can be an expert fighter without ever having had a fight. How do you, or Joe know factually (And that's the key phrase), that he would
ever win a BJJ/Grappling competition at any level? You can guess, presuppose, make bets, proclaim soothsayer abilities, claim you know what's likely, but in the end its not knowledge until it's happened.
Don't give or accept a blackbelt unless it's earned and proven in at least one fight.
Props to Tyrone.