Yes, Funk, you're basically correct.
I forgett the exact details, but the NPC and the AAU went to court to settle which organization had the right to use specific bodybuilding titles.
After that case was heard the NPC was either ordered to not use (or decided not to use) the term "Mr." in any of its titles. (There were no "Miss" titles at that time to the best of my recollection.)
I believe that same court case made a decision which prevented any amateur sports governing body from rejecting an individual's entry simply because he had participatrd in a rival organization's contest.