I just read about the new achievement forum and it is a step in the right direction. But why are you still trying to police your user's thoughts on this kind of forum. (It is bad enough that you try to police it elsewhere!) Seriously... Why do you care?
If two guilds are competing to be the first to finish something, why do you want to spoil it for BOTH guilds by not letting the victor say "Woo Hoo. We pwned you!" to the other? It is YOU who are insulting us with this policy. This policy very clearly and eloquently says to your users that they are babies, too weak or jealous to handle someone else getting somewhere first.
And, if a thread degenerates into "You suck" followed by "No, you suck worse", why do you care about this either? Most people will leave this kind of thread and it will die anyway. And when it doesn't die, there is a reason for that. Because some people LIKE to argue. Why not let them? I really don't see how it hurts anyone. And I do see that it helps all of these conversations when people can speak freely without devoting part of their brain to trying to guess what is appropriate and what isn't. (And, wouldn't it make life easier for you also?)
There are any number of forums and newsgroups that do just fine with no moderator at all... Flame wars happen sometimes. But for the most part, people self-regulate. People learn who the trolls are and stop responding to their stupidity. Threads sometimes deteriorate, then someone moves the intelligent parts to another thread where it happily continues. And the flamers vent their frustrations into nothingness. Everybody wins.
This seems to be a bad policy based on a very narrow view of what conversation should be. I mean, if the people making these decisions are all soccer moms who take their kids to "both teams win" type soccer matches, that's great for you. But it starts to be a bad thing when you try to force your customers (who have a wide variety of different perspectives) to fit into that narrow mold.