Occamy, let's try another course of action. As frustrating as you find the conduct, I encourage you and the clan to ignore such posts. It appears that each time Forum Moderators intervene, the player's goals are met and his behaviour is having the desired impact. If you ignore him, I believe that he will soon tire of the behaviour.
Kcin, at this stage, the threads discussing the Christmas event will remain in those forums. I appreciate that the content may have been around for more than the two week limit but, as the event is only temporary, they are not suited to the Existing Game content forum.