I don't think "they" appreciated being told how they were allowed to make a point. The efficacy of the protest can be debated but only because NO protest is going to advance that discussion in some parts of the country.
No one is telling them how they can make a point or if they have a right to. These are rich and famous people who have a multitude a platforms and opportunity to make a point anytime and anyplace they want. It has been pointed out to them that there are better times and places to make their point then during the national anthem and that doing so is hurtful and disrespectful to millions of people. But they choose to say screw you to these people. Maybe because they're full of s*** about what they say they're protesting about.