If you can't behave civilly with another person you have no business swinging a sword at them. You should protest the event hosting them if you feel so strongly about it. You certainly shouldn't be participating in the event. If you decide to show up and compete against the other person you're already past all that, and now you need to behave civilly with them.

The point is, sure, there are people who don't deserve respect. But respect is a necessary prerequisite for this kind of competition. If you can't respect your opponent you shouldn't be competing against them. You can't disrespect them and also compete against them, you pick one or the other.