negative feedbacks

is there some rule against retalitory negative feedbacks? just curious what the precise rule is about that or if its non existant
Conquer Club, a free online multiplayer variation of a popular world domination board game.
http://www.tools.conquerclub.com/forum/
http://www.tools.conquerclub.com/forum/viewtopic.php?f=6&t=33339
Feedback Guidelines
* Leave only fair and factual comments that relate to a specific game.
* Do not leave feedback for trivial things like missing an occasional turn.
* Do not use foul language.
* Do not fish for feedback (i.e. leave positive feedback to get positive feedback in return).
* Do not leave retaliatory feedback (i.e. leave negative feedback in revenge of negative feedback).