OK, I will try to explain something you should have learned in the fourth grade at a level that ought to be understandable to a third grader.
The Bill of Rights guarantees your freedom to speak and express yourself, protecting you from governmental action. It can never be made illegal, absent an amendment to the Constitution. Every one has the right to "protest".
And everyone else has the right to counter protest. Including the fans that booed the "protesters", the President who felt strongly that their protests were disrespectful, the owners that whined at the President, and the heretofore nonexistent management/ownership/coaching staff who could in the future punish the "protesters" for doing their thing on company time.
The Freedom is from being jailed or otherwise facing punishment by the government. It isn't about any response you might get from other individuals or non-governmental entities.
You have a Constitutional Right to speak. Not a Constitutional Right to be heard.
Or, as I more colloquially put it, you have a Constitutionally guaranteed right to be an as$hole. but no right to compel me to cheer you for being one.