There are plenty of hobbyist-level BBs that get a black belt for punching the clock for 10-12 years and making a slow grind upward over time to something resembling a black belt, even if they would get handled by younger, hyper-competitive purples/browns, monster non-belted guys like Khabib/Islam, etc...
The idea that a pro MMA fighter who has 15 (?) years of training doesn't have the mat time required to pass that standard is a little silly. In terms of pure technical knowledge, service, being able to teach others, etc...there is no way for anyone here to know that.