Don't forget even from the time of John L. Sullivan (and before) boxers had the law coming after them. Sullivan was arrested several times and taken to jail. He was actually convicted of engaging in an illegal prizefight and sentenced to serve one year until he won the case on appeal. Politicians in general had it out for boxing. Why? Cause they are pompous assholes who like to tell everyone what they can and can't do; and they love the spotlight and the public notoriety they can get by going after the champ. It caters to their base of voters who hated boxing and the folks the sport attracted.
