You can be in the body of the Kirk and be isolated. No one is being pleasant or friendly or engaging with him.
He has joined in because he is there. Could you imagine the bitching if he hadn’t crooned along? Danced a bit? He isn’t stupid. He knows he is merely being tolerated at best.
If they had the choice to have him sieve they creek for leaves while they had fun, I believe they would 🤷🏻♀️
I have said what you mentioned in your second paragraph. Also. They are so worried about themselves they are blind to the fact that they showing a poor side of themselves.