Harassment in the sense of targeting someone in chat with vile and hateful language I can definitely see being against the games terms of service. With much of the chat being between players rather than characters that is certainly a system I think the Developers rather than Kingdoms will have to monitor and control.
However, in character actions in the game should be through the Kingdoms laws only. There are no actions that another player can take that do not have story tied to them, that do not develop the world. Yes they may put another player at a disadvantage but that is really part of a dynamic world such as this. The word griefing should be banned as it just does not fit here.