The NFL league office is organized as a 501(c)(6), a part of the tax code that exempts thing like business leagues, chambers of commerce and trade associations.
http://www.npr.org/2014/01/18/263767372/the-nfl-big-business-with-big-tax-breaks
The Feds can always remove the tax deductible write businesses get with NFL Box seats, tickets, etc...
Furthermore, the taxpayer money they received to build stadiums should be reclaimed on the grounds that the NFL is now political.
Finally, boycott all companies that advertise with the NFL
The NFL is no longer organized as a non-profit. They changed that in 2015. It doesn’t matter anyway because they don’t have any profits to report. The other tax breaks you describe apply to businesses that patronize the NFL, not the NFL itself.
Oh darn, I should have read your post first. I said the same thing about corporate tickets