They can protest all they want, call a press conference, buy ads with their millions or hold a sign on the street.  When they show disrespect for the flag and national anthem is when they cross the line and introduce divisiveness into the game.  The flag represents their right to speak out, why would they piss on that?  Yes, they technically have the right to protest this way just as flag burners do.  But I guess the fans can draw their own conclusions as well over paying for their multi million dollar salaries.   Just for comparison, I don't expect to see anyone taking a knee at a hockey game.