I, for one, am not saying that this minor patch is what I had in mind for the patch before the Siege, but oh well, it's what I'm getting.
Right now Garrosh is the enemy, but so are the Darkspear Trolls. However, like the old saying, "the enemy of my enemy is my friend" so the Alliance and the Rebellion are going to tolerate each other until their mutual enemy is dead.
This can also be seen in the history of our own world. The USSR and America were allies during the second world war due to their common enemy in Adolf Hitler and !@#$ Germany. So in 5.3 the Alliance and the USSD (Union of Soviet Socialist Darkspear) are going to play nice until Adolf Hitler, sorry, I mean Garrosh Hellscream is dead.