Hi Kerry, thanks. I think your logic may be more statistical than empirical. Yes, actuarially speaking Biden's age runway is totally running out but practically speaking he seems to have objectively achieved more than most far younger Presidents. Also, he knows himself best and I don't think if he was in a state of confused brain fog unable to comprehend the job that he or Jill would desire to run which means he's feeling strong and focused and capable. In fact he is demonstrating great courage and strength to run.
I think what he really wants is a Democrat Congress so he can actually achieve his dreams of voter protections, immigration reform, assault weapons bans and codify Roe and more. Transformational.
And regardless of what we say on Biden, the opposition is completely unhinged and deeply flawed and a far greater risk than Biden's age. On top of that Harris, while not the top in campaign skills is extremely competent, rational, professional, knowledgeable and responsible and can easily hold the fort should Biden have insurmountable issues.