Yeah, what people have said. No exploits occurred during Sinestra and Nefarian kills. Sinestra was killed like it was created at that time by Blizzard and top guilds always figure out the most efficient way to down bosses fast so druid stacking was the best. It was by no means an exploit. Also, Paragon was the only guild who downed Al'Akir 25man pre-nerf, after which so many kills occurred.