It’s a counter-protest to Kaepernick’s protest against the National Anthem. What better way to show support for America than to wave an America flag to offset the wrong, jerk, idiot Kaepernick who doesn’t know enough about America to know what he’s protesting against when he disrespects the National Anthem.
There’s no such thing as a Right To Protest at an NFL game. The government is not in charge. The stadium is controlled by the NFL, not by government. The NFL pays for the stadium and for the players. They can simply tell Kaepernick to stay in the locker room until after the anthem is finished. They can tell him not to suit up or not to come onto the field but of course they can let Kaepernick continue to prove he’s just another ingrate who doesn’t understand America.