Oh, I'm totally with you on not understanding WHY Castiel didn't just tell everyone that he had raised Sam. It made no sense what so ever. Cas was closer to Dean, so I can't see Cas suddenly deciding that Sam's choice to wander away meant that Cas shouldn't tell Dean that Sam was back, and something was wrong. I can only see two reasons. One is that he was understating his knowledge of something being wrong when Sam first came back. That he realized right away that Sam was soulless and didn't want to admit to that big of an OOPS!. The other reason would be if Cas deliberately brought Sam back wrong. If he had already been working with Crowley getting a totally focused hunter would have made sense, but since the alliance hadn't happened yet that doesn't make sense either. It is the one loose end that really niggles at me.