Let me sum up. BYU looked the other way on many things when it came to McMahon, so they should look the other way on all things when it comes to McMahon.
If your point is that BYU exploited McMahon by looking the other way because he won them a lot of games, you seem to forget that McMahon was a first-round pick in the draft, started and starred for an NFL team for years, won 2 Superbowls, and made millions of dollars. I'd say McMahon made out pretty well in this deal.
I still don't understand why an exception should be made in McMahon's case. He had every opportunity when he was in school and in the years following to get his degree. Nothing in his circumstances says "exception." Exceptions should be reserved for students who, for whatever reason, couldn't complete all of the requirements but merited inclusion in the HOF anyway.