Let's put it into another environment and see the player's actions out of place.  Imagine if you are at the grocery store and the cashier has a political statement on their shirt and is promoting that statement to all the costmers.  Same as a bank teller, a doctor, dentist, fast food worker, etc.  Imagine during the start of a  movie, a theater employee starts yelling some protest slogan.  Or your office colleague does the same.  It would be inappropriate. Same inappropriateness with the pro players on any team. They have a right to protest but on their own time.