If Tiger Woods said "I'm not going to compete until all the Competitors doe this, this and this", or if Federer said "I won't play against Nadal unless this this or this" or the Lakers said, "I won't play the Cavs unless these demands are meet", we'd look at them like they were crazy.
Boxing have rules, regulations, and testing, also the States Athletic Commission does to. Its not like it's some backyard brawl Pac is following all those but with Mayweather is imposing his own rules But since Mayweather IS boxing right now he's basically have the power to do this.