With regards to the griefing...would it help if the debuff was only triggerable if the pull was initiated by a group of 4+ people?
I'm not sure what other kinds of problems this might cause, but it seems like it would make it a lot more difficult for that type of griefing to happen.
I think the boss should only be tauntable by anyone currently in the group currently fighting it, with a debuff or another buff.
(thats only a fix to same faction griefing and doesnt fix the issue about the other faction trying to kill you during the fight..)
P.S. to Bioware: World Boss suck, it always did and will ever be an issue in a any game. Stop wasting resource on it and make it instanced.