You have an idea on your head based on nothing but your gist that somebody has to be "personally examined" to form a diagnosis, that's simply not correct when there is the greater good of the community/nation/world we all live on to serve. There are exceptions to most rules.
Normal people think Trump is playing a role, its only partly true. Truly grasping and certainly seeing patients adversely affected by him they are inclined to warn the community of which they are a part and also at risk.
The idea of "duty to warn" has been examined many times and it always lands on once a psychiatrist (or other therapist) believes a patient is a serious danger, they have to speak up.
"Justice Matthew Tobriner of the California Supreme Court, in the now-famous Tarasoff cases, who created a therapist-specific version of the legal “duty to warn” of tort law, overriding the therapist’s ethical duty of confidentiality. Writing for the majority in his 1976 opinion, he declared that in “this risk-infested society we can hardly tolerate the further exposure to danger that would result from a concealed knowledge of the therapist that his patient was lethal.”
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And they were correct, Trump was lethal to tens and likely hundreds of thousands. If he was in again, another disaster would unfold as the parts of him that are not an act will ensure that.
It is their own medical society, the American Psychiatric Association, stating that it is unethical and improper for psychiatrists to push claims about an individual they never personally examined.
How will you like it when a group of psychiatrists -- all of them registered Republicans -- push claims that Biden is unsound of mind, has dementia, and is unfit to be President. There are reasons the Goldwater rule is in place -- prevent quacks from pushing their "analysis" for political or personal purposes.