When it comes to world bosses, as a team we are aware of intentional griefing. We are working on ways to improve (or should we, reduce) briefing when it comes to world bosses. However, not every possible scenario can be covered from all angles. Level 1's on Kazzak? easier to deal with. Same faction griefing? similar but can be a bit more challenging while still remaining something that can be addressed.
However, when it comes to different factions working together that is something that would be extremely difficult to "police". We are here to help the server as best we can, we can't always be police officers. Honor trading in battlegrounds is against the rules, and "easy" to isolate and determine who is doing what. When it comes to a world pvp environment, how can you enforce one faction not killing another on sight? We as a team cannot force players to kill each other on sight. In this thread there has been both claims that the rival factions were working together, and claims from those within those guilds that there was no direct collusion. So, as a team what are we left with? We were not there to witness this behaviour, and even if we we had been and if we did deem that "working together" between factions was against the server rules how do we provide suitable evidence? As an example, a member from Risen and the guild leader of Onslaught has stated in this thread that they engaged in pvp with each other. So how do you enforce something where there is no clear direct evidence?
That is the challenge that we as a team would face with world bosses if cross faction co-operation were not allowed. We could suspect that factions are working together, but without clear cut evidence it would be very difficult for us to prove it.
So if any players have an answer or ideas on how such a rule would be enforced then as a team we would be happy to discuss it amongst ourselves at our next meeting.