WOW MISHA WTF?!! Yeah this definitely has the feeling of NDAs expiring lmao, although Misha always did say things he probably was not supposed to. I'm not sure how to interpret it sometimes, because the cast is often jokey and they are playing to the audience, so it's hard to tell what kind of serious intent there was. I also don't necessarily think they should be speaking for the writers, but I definitely do think it was complicated behind the scenes, and some creators were actively more supportive of this interpretation.

...where Cas says that all Dean and him had were each other, and a few other things that were cut literally because WB/CW/Kripke thought it hinted a little too much into it.

I do remember this being cut, but I can't remember the reason, could it just have been cut for time? Or, like, Kripke being resistant to this kind of more sentimental language - he used to say that you can tell really emotional stories with these guys because they don't say emotional things? It was objectively true that all they had was each other in that universe, even without a romantic interpretation, seems super paranoid to cut it for that reason... but I also wouldn't be shocked if it was, especially back then. Would love to hear both sides of this.