Your thesis is based on the assumption that Mr. Biden is cognitively incompetent. I see no evidence of that. He has always had a problem with a stutter and perhaps a weak form of aphasia, but these are not indicative of cognitive incompetence.
Here’s a quickie primer on cognitive performance with age: intrinsic cognitive capacity peaks around age 30 and then begins declining. If you measure overall cognitive performance, however, that peaks around age 60 to 70. Why? Because the dominant factor in overall cognitive performance is knowledge, not cognitive capacity. Obviously, you need both knowledge and cognitive capacity, but knowledge is more important for most situations. That’s why most of the people in leadership positions are in their sixties or seventies. Sure, they’re not as fast as those twenty-something whiz kids, but they still make better decisions.
Ms. Pelosi is a year older than Mr. Biden. Do you think that she’s senile? Supreme Court Justice Ruth Bader Ginsburg is 87 years old, and she’s still writing opinions for her job. Do you think that she’s senile?
So intrinsic cognitive capacity (there’s a technical term for this, but I’ve forgotten that term because I’m old) declines throughout adulthood, but knowledge continues to rise, with the overall peak coming in one’s sixties. Mr. Biden today is not as smart as he was ten years ago, but he’s still way, way ahead of, say, Ms. Ocasio-Cortez. She’s sharp as a tack but doesn’t have enough knowledge to pack much punch.
I’m 69 years old and struggling with cognitive decline. I forget words and am no longer capable of writing big computer programs. But I’m still a hell of a lot smarter than any of the thirty-somethings I encounter. It’s not because I’m a genius; I’ve just learned a helluva lot more than they have. I’ve made every possible mistake, and they’re just beginning to accumulate a collection of edifying mistakes. I can run circles around those kids. And as far as political nous goes, my guess is that Mr. Biden can still run circles around most people.