It’s just bare motivated reasoning. Their football team had the ball so anything they do is okay. Meanwhile when Reagan started showing dementia symptoms they made him go get evaluated.
Of course I've heard him speak, he does press conferences every single day, sometimes for hours. He takes questions all the time including impromptu ones on Air Force One. He did 3 hour podcasts during the campaign, he's incredibly poised and this has been affirmed by everyone from Jensen Huang to Modi to Tim Cook to Bill Maher.
Biden was kept hidden and carefully managed and his staffers had to cut him off and remind him of the current year. You may not like Trump, but everyone that works with him closely, recognizes he is more intellectual than his public persona would seem to imply.
So why does he sound like an incomprehensible moron? And why are all of his plains straight up broken, like tariffs that would have been appropriate to stop the destruction of American industry twenty years ago, but at this point are just closing the barn door long after the horse moved away? If he's really some wise leader and only rambled incoherent word salad to appeal to the "common man" and get elected, he has now been elected. Shouldn't he be revealing his wise persona, leading, and bringing the skeptical into the fold with some intelligent policies?
Most elderly people are capable of sitting around for hours rambling, especially on political topics. In fact, what's difficult is getting them not to. Occam's says that affirming the emperor is definitely wearing clothes is just the type of politically correct fluffing that happens in every autocracy. Lying to ingratiate yourself with flattery certainly costs less than paying larger bribes.
LOL. Sure he can ramble for hours. But if you read a transcript of any of those conferences, he's literally incomprehensible, can't string more than two logical sentences together. It's just a jumble salad of key trigger words. And when he does present facts, it's either incorrect or an outright lie. It's an embarrassment, frankly.