That's a dope theory.
Would that mean he's making the final commands to kill the Night's King and its echoing backwards into the mind of the "Mad" King?
Something like that has got to happen. Nothing about Bran makes me feel comfortable, and so I imagine he is a neutral party that they are kinda foolish to just keep around without question. He's useful, but he very clearly knows more than he says and has his own motivations.
Jon isnt going to press that too much, since Bran still is his little brother who is crippled.