I think at this time, we are going to have 2 very flawed and undeserving candidates. While Biden isn’t firing on all cylinders Trump sometimes seems his fuel line is plugged too. I think the offset is Trump appears more energetic. Both have been famous for word salads, forgotten names and events and inappropriate statements. It’s quite sad. I do I agree he likely will not be the ultimate nominee.
I once had dinner with a self-made multi-hundred millionaire (the sheet music industry, of all things) who was in his late 70s, and this guy also was loud, profane, a big spender, and didn't care what anybody felt about it (the "I can buy this place" attitude if people complained).
It comes with extreme success, the kind that we can never really understand. So I don't chalk up Trump's comments to a mental deficiency; it is arrogance, but an arrogance that comes with accomplishment and success.
The "word salads," as you call it, are different between Trump and Biden/Harris. With Trump, he often meanders in his speeches, tangentially deviating from his main thoughts to make side points but ultimately returning to them. With Harris, she's just vacuous and fills the space with extra words that mean nothing. With Biden, he's caught between forgetting the subject and flashes of anger. It's a common trait with dementia patients, they remember things from 40 years ago but forget what happened last week. That's why Biden can remember he was talking to the French President, but could only recall the name of the President from many years ago.
It's interesting that you don't throw Obama into the mix. Obama was called the TOTUS, "Teleprompter of the United States." Obama was a very eloquent speaker when augmented by a teleprompter (if you can look past the ping-pong effect), but he was reduced to uhs and ums and ahs when he had to speak extemporaneously. During White House press conferences, his staff eventually placed a large-screen TV behind the press seats so that Obama wouldn't be seen turning his head left and right and left and right when he was speaking on camera.
-PJ