I have a better vantage point on Biden. Know folks who had regular interactions with him.
Big mistake politically for Biden to have contemplated a second term. The electorate perceived Father Time had got the best of Biden.
His mind and wherewithal was still very good throughout his presidency. He was on the phone a ton. He wasn’t being handled by handlers.
And he achieved a ton on his watch.
Contrast Trump’s first 20 months. A shitshow.
As to your premise that 80 is too old to be President, I agree.