Funny you should mention this, but I've flown with a couple of guys who were bummed about having to retire, but holy cow were they off their game whenever any kind of weather moved in. Not that they were incompetent, but they were just slow processing the information. It's just a part of aging that you refuse to accept.
Another particular captain was adamant against age 60 rule, yet he couldn't land at night to save his life.
If we are forced to fly with guys over 60 and they are anything like these couple of captains, I know more of us will speak up and strongly urge these fine folks to retire.