I live in a rural community filled with farmers and FiFo workers (fly in | fly out mine and rig workers) with a median age of ~ 60 years.
My father has worked hard manual labour his entire life, he only recently stopped splitting wood and climbing ladders. He was born in 1935.
He's not unusual here, many 60 and 70 year olds, 80 year olds even, are still active on the land here.
Rephrased, it's just as problematic, albeit with a kernel of truthiness:
Clearly some of us are still fully capable of doing manual labour at 67 but those who have spent their lives doing software "engineering" have usually accumulated some significant mental burn out by that age. They need a break.Quite an assumption on your part.
Despite having serious mathematical qualifications and several million SLOC of code behind me, I've also worked cattle stations, mine sites, and been part of SES and St. John's Ambulance crews (first responders to accidents).
That said, to address your question,
he's not worked with either Aaron Swartz nor Terry Davis.
The outside view is that the US has minimal Occ Health & Safety enforcement in labour and was late to the game in any case.
Given that, software work at 67 should be well within cognitive limits.
(I'm actually not sure if I'm being sarcastic)