I agree it’s taking it too serious to let the actions of a rival coach affect you in any way. It’s dumb. But it is a rivalry and that is what happens in a rivalry. Dumb stuff that you allow yourself to worry about. It may be embarrassing later that you cared so much about a game that you got in a fight with opposing fans or that you ran to and got beat up by another team’s cheerleader but it’s a rivalry. It’s beyond the normal rules of life. People act immature and petty. People care.