I think it’s a different ball of wax when we’re dealing with public figures because there’s always a certain amount of image management considerations that go into whatever they say publicly.
Also, since most of us don’t know Biden personally, we are not in a position to make an accurate assessment of any mental health issues he migth have. Most of us probably don’t have the qualifications to make a diagnosis anyway, and if we did perform an actual assessment, confidentiality concerns would forbid us from ever talking about it.
Finally, all kinds of people who are not narcissistic blame others (especially politicians!) for their problems. It’s a type of learned helplessness acquired through trauma or a kind of upbringing where their concerns weren’t heard and addressed. If you frequent this space, odds are good you have yourself engaged in this behavior. It can take some good hard work in therapy to figure out that you actually have power… and where your responsibilities actually lie.
While it can be fun at times to speculate about all the mental health issues the politicians that annoy us might have, for the vast majority of us it will never be more than idle speculation.