Agreed. I've flown with guys in their sixties who do just fine. Not coincidentally, they're ususally the guys who still exercise regularly and eat sensibly and don't polish off three or four beers every night in the lounge at the hotel and who take responsibility for their own health. The guys who suck are usually the ones lugging around the big beer guts, who jones for a cigarette after two hours in the seat and who can't keep it together when the unexpected comes along.
You'd think the FAA could develop some kind of cognition/reflex screening that tests a person's ability to multitask and concentrate, etc. Either that, or they need to significantly up the requirements for holding a first class.