This is murrica and we stand for this song that was written during a war that was going on many years after our country was founded!
No. It’s not just a song. It’s the National Anthem of the United States of America. Its words have meaning. Its symbolism has meaning. It is not just a song. To rob it of its symbolism is to say that respect for one’s country is pointless and holds no value. It’s to say that the people who work and fight to give us the freedoms that we have were doing so without need nor purpose, and we do not honor them because who gives a crap.
But to show protest of injustice by sitting during the anthem is a legitimate form of protest, and is not inherently disrespectful toward the country itself so long as the purpose of protest is made plain.