Why has a prospective U.S. Presidential candidate been blasting UFC labor practices?

Don’t question Andrew Yang’s UFC fan bonafides. The New York native planned his bachelor party around the TUF 12 Finale in Las Vegas back eight years ago. He’s been a hardcore enthusiast of mixed martial arts for more than a decade and remains so.
What can be questioned is why Yang — a potential U.S. Presidential candidate in 2020 — has taken to Twitter recently to slam the UFC’s labor practices and how much (or how little, if you ask him) the promotion pays