I'm willing to bet that most if not all that are upset about it, never served in the military either. Remember that it was a marine who suggested the kneeling.
Some people do not know there is a little known rule in the NFL abt standing at attention for the National Anthem. It is not even enforced. But a team can have penalties to an automatic forfeiture of game if team members do not stand for the National Anthem.
I can't understand why in "the land of the free" people are getting so upset about others doing as they want.
More like "Land of the free as long as you do what I say"