Wrong, psychological conditions are complex a diagnosis cannot be made watching TV or reading press releases. I had a long discussion with my son( a Psychologist) about this and he agrees. These golf making these diagnoses are grand standing. A diagnosis is done over several in depth sessions with the individual over a period of time with followup review to confirm etc.
I often get the feeling we talk past each other when debating an issue. No diagnosis is being made here. The good doctor is not saying what, if anything, is wrong with Trump (other than him being a dickhead). He is not making a diagnosis. He is simply ruling out a diagnosis on the basis of Trump's public statements and behaviour.
Look at it this way: A plane crashes. On the way down, the pilot can be seen to be making desperate manoeuvres to regain control. An aviation expert says, I don't know what went wrong, but I can rule out pilot suicide.
If Trump does and says things that someone suffering from pathological narcissism would never do or say, then you can safely conclude that whatever may be wrong with him, it isn't that. You don't need to do a full diagnosis of someone to rule something out. You do need a full diagnosis to rule something in, but that is not what is happening here.