He'd gotten Dean out of Purgatory, just like he wanted to. His other self coming in and telling him they needed to end the war and sucking up souls wasn't something that he'd planned on happening.
And it was scary. Concerning, too, since it could have just as well been him in his other self's shoes - with all that power. Nothing good could come of it, Castiel knew.
Dean seemed to be hiding behind him which was just fine. Putting himself between all that power and Dean was something he would have done in the first place. He opened his mouth to say something to the other Castiel, just a few words when he was shushed by Jimmy, mouth closing immediately and looking curiously at the human.