If I understand you correctly, you're saying that Trump is elderly and has dementia, therefore, he should not be prosecuted for anything but it's still OK if he runs for president.
No, it's not okay that he's running for president.
It's not okay that the GOP knows what a disaster he was, and are getting behind him anyway.
Trump is a sign that our democracy is broken.
He absolutely should be prosecuted for his crimes, and if he wants to plead diminished capacity, he can.