That seems extremely anti-competitive. I wonder if that rule could be challenged.
[2] 26 U.S. Code § 501 - Exemption from tax on corporations, certain trusts, etc.
[1] https://www.law.cornell.edu/uscode/text/15/1291
[2] https://www.law.cornell.edu/uscode/text/26/501
There are also a few more places the Code references football: https://www.law.cornell.edu/search/site/football?f[0]=bundle...
[1] https://en.wikipedia.org/wiki/United_States_antitrust_law#Sc...
[1] http://espn.go.com/30for30/film?page=small-potatoes-who-kill...