I think the angels are all a little unstable and it's more apparent the higher up the food chain you go - that's what happens when you create a race of beings expressly created to follow orders and then flounce away for no apparent reason (good going, God!) The entire Apocalypse is the higher ups flailing around because no one's there to tell them what to do; they pretty much cling to Apocalypse because they know that's supposed to happen and go "That. Let's just do that." When we meet Cas he's relatively sheltered from that because he still has commanders (Anna was a above him and fell fairly recently, Zachariah's his superior, the Archs. Even with Uriel I always had the feeling it was more like Cas was the lead detective than actually outranked him.) Look what happens when he's put in the position of giving orders himself!

Castiel's naivete is appallingly childish in this story.

Cas is canonically naive even for the angels, Uriel and Zachariah both treat him that way. And he has a very hard time letting go of people he loves - look at how he goes to Anna for advice even though he knew he was supposed to despise her for falling. (That's why it's such a gut punch when he does betray her.) And with Uriel, after finding out Uriel's a traitorous murderer he still doesn't draw his sword. The guy believes.

Even though I do like the idea of Anna and Balthazar rescuing Castiel, I agree with grasshoppr_molly. The only way Castiel could ever truly leave that room is if Dean left with him.

Even if they took him physically he'd still be back there mentally. (I don't think there are enough words for how badly Balthazar would take all of this.)