Well since you don't know that he is, why even bring it up? And how old are you to consider 64-65 as "golden years"? Half the country's population is that old, LOL! Where does your concern leave you for Romney (age 60), Giuliani (age 67) or McCain (age 70). Must they too be concerned about their respective marbles because they've reached their 7th decade?
There is much more to be said for the wisdom that comes from age and experience.
As for participating in every debate for the "practice" you need to realize that debates are rigged against republicans and for democrats. They are prime opportunities to mis-speak, be photographed and portrayed unflatteringly etc. While Fred will participate in many before it's over, he's lost nothing and gained everything from declining in these early ones.
And I expect Fred knows very well the amount of preparation and rehearsal required when the time comes. He's going to do fine.
Excellent post!