Ok so, I actually understand why Nick is so upset and does what he does. Now, that doesn't mean it's the right to do, but most people don't do the "right" thing anyway.
I'm thinking this is some of the effects from his kidnapping. It's a bit of a stretch and I don't think it will be mentioned at all, but it did have an effect on his personality and everything, so I personally think thats a part of why he makes such a rash decision.
Also, Grissom has always been his supervisor, and Catherine a co-worker with a little more authority than himself. Grissom treats the team better than Catherine does (I'm sorry, but he does. Not a whole lot, but he knows how to handle things better) And now she comes in and is doing something really shady, right or wrong, and is then pulling out the "supervisor" card that he kind of feels doesn't belong to her.
It's the same idea with a step parent: a lot of children refuse to except anyone as a replacement for their own parent. And when the step parent starts trying to control the child, the kid freaks out and feels anger towards the person and wants to rebel against him/her.
It's just the way humans are. So, I understand why he is doing it, and I don't dislike him for it. Apparently, she does something that really gets to him.
As for Warrick and Sara, I think they are also upset about what's going on, but I don't think that either of them would want to take a huge step like that. And I think this is where are part of Nick's past experience comes into play. They see their friend that they have known for a long time really upset about something, and of course they're going to go with him. Think of what would happen if they would have rejected him. It would not have been good, and they know that.
Now Greg knows that too, but I think he sees the danger in it, as well as the fact that he is still feeling repercussions from what happened in Fannysmackin, and I've always seen him as a being a mini Grissom, and Grissom would never go for that. But Greg's the newbie and so, he goes with it. Well, sort of. He shrugs so.. I don't know. I think his relunctantness will come into play a little later in the episode, or the ones coming up.
..and the list is endless. where they've covered and stuck up for each other!!! no matter if Grissom is here, or the new guy.. their a tight group, and love each other!!!
