Bulls#it. Safety is just a convenient excuse, and always has been since anyone who questions a safety issue is immediatly demonized.
Sorry dude. I've flown at every hour around the clock in turbojet aircraft with those in the early/mid 60's and those at AA approaching age 60.
In the post age 60 group, most started showing signs of aging affecting their performance. This was most evident after long duty days or back side of the clock flying.
Take a look around at the aging in everybody. It's sad to see friends, relatives and neighbors all start the slide. Just drive around in Florida for awhile.
Yes, there is a safety issue, but social engineering always seems to take priority, especially when it's how some group "feels" about an issue.