If you wish to say strong words to someone who may have upset you, it would not be usual to do so in a public place. It would not be considered polite to embarrass those watching and listening.
The Mudcat forum is a public place. If the personal messages, that Max has provided, are used you can do all the name-calling you wish and no one else need know.
In the case of a 'guest' causing offence, it is not possible to send a personal message and the best method to deal with this is probably to ignore it.