It would be ageist to say any old guy must be past it, but not ageist to say its a relevant consideration. I knew a few professors who were outstanding figures

It would be ageist to say any old guy must be past it, but not ageist to say its a relevant consideration. I knew a few professors who were outstanding figures at their peak, but who continued teaching into their 80s. It was obvious to everyone around them that they needed to retire years before they actually did.