Amateur orgs affiliated with the amateur IFBB in other countries often threaten to ban athletes who compete in other orgs, with limited success. Lots of people compete in NAC, NABBA, WABBA, IBFA, etc., and the IFBB.
However, because of that 1982 lawsuit between the AAU and the NPC, it would be illegal for the NPC to do so. Now that settlement mentions Jim Manion by name, stating he cannot ban anyone for competing in another org. I wonder if that applies to his new job as head of the pro IFBB.
As far as the original thread, the following people competed in PDI sponsored contests and later competed in the IFBB:
pro IFBB
Sami Al Haddad
Michalis Kefalianos
James Llewellin
Julio Cesar Balestrin
Sean Allan
Valentine Jabes
Eduard Duque
amateur IFBB
Charles Mario-Soares
Orazio Salvatori
Simone Meiattini
Julio Cesar Balestrin
NPC
Tomas Rey Jimenez
George Maiorano
Anthony Forgione
So much for threats of being banned for competing in the PDI