there is absolutely no way to prevent discussion

I didn't mean: "you are not allowed to discuss this". I meant: "this is our decision, and it's final; you can discuss it if you wish, but it won't change the outcome".

In other words, I recommend against deciding a penalty for a specific case by a community vote. Because it could easily become a poll about whether the offender's faction is more powerful than the victim's faction, or vice versa.