Correct. You could believe (and perhaps even be right) that a court has no legitimate authority, but authority is commandeered through violence. There is no practical difference in asserting your sovereignty when you’re in court as when you are being mugged by a robber. In both cases you either comply and play the game or be prepared to use violence and, in the case of the state, that would likely require you to use constant violence for the rest of your life until you’re far far away from the long arm of the law.