I find that people complain about politics at sports when the politics are something they disagree with. However, if we see politics that we agree with, then all is fine with the world and we don't give it a second thought.
What would happen if fans are concerned about America's military budget & overreach and they complained about the use of military displays at games (such as the National Guard presenting the Colors or the military being used in advertising)? Would those fans be allowed the same courtesy of raising their concerns about politics at sporting events? I highly doubt it.