Shrinks debate putting Bipolar Disorder into the Psychosis category.
It's all a tempest in a teapot for me. All of our diagnoses in Psychiatry are of dubious validity. They have two purposes: 1) Something to write on an insurance form and 2) a starting point for research to find out if they make any sense.
I do not even think that Schizophrenia is a "disease" per se. It's a handle for a lot of different strange things that we understand poorly.