Haven't read the story yet, but added it to a list to check out later.
FYI there is no such thing as a black belt in mixed martial arts. Most MMA fighters learned Jiu Jitsu at some point, but other than that they have belts in a variety of disciplines.
Mixed Martial Arts mixes a variety of skill sets and tests them against each other. MMA is simply a showcase that allows fighters to test combat skills using whatever they know... without being disqualified for the equivalent of using a karate move in a wrestling match.
My kids studied Gracie Jiu Jitsu for a while. I think JJ is a good choice for anyone ...including women, kids, and anyone with a physical disability who wants to defend themselves effectively - while avoiding expulsion from school or legal hazards. (My son was in a zero tolerance school and got a 1 page essay on conflict resolution.)
Jiu Jitsu was founded by someone with physical limitations. They trace their liniage to a renowned Judo expert of his generation. Gracie Jiu Jitsu is considered the most true to their roots.
Jiu Jitsu also had some of its early start in literal street fighting. They advertised by challenge matches with instructors of other martial arts schools ...essentially beating them up to show their training was better. (Crude, but convincing.)
JJ students are known for being able to defeat a black belt in another martial arts type... without having a black belt themselves.
Good manners prevail; online advertising and word of mouth are current methods of drawing in new students.
Still, wild stories about the old days are entertaining. There are also young fools (now & then) trying to make a name for themselves who start something they shouldn't.
