Originally Posted by
Amorise
He's definitely guilty of knowing about the theft of the Divine Bell and failing to properly police his people.
But he was temporarily possessed by the Sha which draws out the victims repressed emotions and makes them visible to all. Whether it be doubt, anger, fear, etc. If he was possessed and stated that he hates the Horde and wants the Blood Elves to leave it, then that's his thoughts and feelings. Him doing a 180 and being a Garrosh loyalist is just bad writing.
It's likely that Aethas knew what was going on and was going to use the information as a power play, but Jaina traced the theft and went ballistic before he was able to. Something like "hey Jaina, I know the names of the Horde loyalists and who stole the Divine Bell, I'll give you the names and let you have your way if you help to get us out of the Horde."