I"ve said this on another thread, but it goes here just the same. If a TV actor on a sit-com (a member of AFTRA) gets a part in a movie and becomes a member of SAG in the process, does he get fired from the TV show because he acted in another union? Of course not! Not in the entertainment biz. Actors are free to make as much as they can.
Bodybuilding is not a sport. It is sports entertainment (like wrestling), so the participants should be treated as entertainers and not athletes. Once you do that, then all this sports federation mumbo-jumbo, which doesn't mean shit anyway, is irrelevant and then everyone can endeavor to make as much money as they possibly can. If the IFBB wants to sign athletes to contracts and pay them to compete for them, then that is another story. Right now, bodybuilders are independent contractors/ free agents. The IFBB's rules might say one cannot appear outside the federation, but now the legality of those rules is going to be explored. I think this is going to get interesting.