OMG do I really have to explain this? The Goldwater rule specifically pertains to psychiatry, not cancer or heart treatment, etc. But I'm not asking you about a judge evaluating the rules of a psychiatric organization - it's much simpler than that...
Have you heard of things like second hand, third hand evidence, hearsay, etc? The legal question is what is the worthiness and reliability of a medical diagnosis made by a doctor who has never even met a patient, much less examined him? You don't think a judge would have their own opinion on that?? It's their job to rule on the persuasiveness of the evidence presented! Judges didn't tell the election officials and experts to sort it out themselves - they made rulings based on the quality of the evidence presented to them by Trump's lawyers!
I am asking if a lawyer was trying to prove in a court of law that someone was psychopathic, and as their evidence they used a doctor who had never examined or had any relation with the patient, what do you think a judge would feel about about the worthiness of that type of diagnosis? In my opinion I think they would believe that's terrible evidence, but just like Trump and his election lawyers, what can you do? That's all you've got!