WotLK - Disable Preform AV Enabler (from server core)
Ok so I'm pretty sure we can all argue that the stupid addon is destroying pvp.
Regardless, instead of going into that, im gona provide a solution to block that **** without even bothering with detecting client stuff or addon presence.
What you do is:
1) Whenever a Raid queues with 6 or more people, meaning: If a queue is made while inside a group that has 6 people or more, prevent all of its members from accessing the queue (Throw message to client "You cannot queue into BattleGrounds with more than 5 people").
Problem solved.
Aight.