Whether or not Matthews actually follows through with his threat is still to be seen, and of course, that's assuming the National Football League passes a rule saying players must stand for the anthem, which may or may not happen.
The posting has since been deleted from Matthews' Twitter account, although a screen shot of it was saved by Paul Kuharsky, a writer who covers the team.
In recent weeks, players have refused to stand during the anthem to protest racial inequality. Matthews, the Titans' leading receiver, has remained in the locker room alone over the past two games while the rest of the team stood for the anthem. It was a stance started by Colin Kaepernick, but the protests became a national debate and an NFL wide phenomenon when president Donald Trump called protesting players sons of bitches.
"Moving forward, I don't want this to be a publicity stunt", Matthews told ESPN last month. He has begun following the path of college teammate Colin Kaepernick, who led the charge of National Football League players protesting racial injustice and police brutality in this manner. "I fully stand with my brother Kap, and I plan to continue to do that". Why is it anti-American to exercise the right of free speech, while many drape themselves in the flag hypocritically while trying to deny others the freedom to exercise that right?