I think it's always best to deal with a situation right then and there. If a person is being rude and disrespectful to the judge and/or a member of the show committee and/or other exhibitors, it's up to the show committee to decide how to handle it. (ETA - The judge does have the right to excuse a person from the ring if the behaviour you described is taking place inside the show ring.)
I had an incident once where an exhibitor came to me (the judge) at the very end of the show and became extremely rude and beligerent in my face. I was talking with the show committee at the time, so they witnessed the exchange between us. I tried to calm the person down, but they would have none of it, and eventually stormed off. I wrote up an "incident report" for the show committee, and was informed a few weeks later that they had decided to ban that person from the show grounds in the future.
If you're referring to an open show at one of the fall fairs for example, I think most of them have rules prohibiting such behaviour, and the fair board reserves the right to withhold the payment of prize money or some other such consequence. I don't have any of the fair books in front of me right now but, if you do, it might be worth looking up for future reference.