On behalf of all old people: Fuck that, and fuck the idea that cognitive performance alone should determine whether someone in our industry can eat.
Because as much as we love to tout that every programmer is living with a house and a mortgage and a happy family, I happen to know for a fact that some are struggling to eat.
Eh. Not exactly an objective viewpoint, I know. But to maybe drain away some of the energy I just threw into that: Being old is our shared destination. It'll happen to you too. It'll happen to me. How is this a productive outlook?
I've known some amazingly productive old people. I learned from one of the best in the gamedev industry. He was my mentor, and basically a mini carmack. When I hear statements like this, I cannot fathom how people believe this myth that old people are inherently less able to kick your ass at programming.
I really hesitate to bring this up, but there's this dopey argument that HN trolls love to bring up, where they point to a certain area of science and say "Look! Black people are inherently dumber. The science says so." Yet the one black man that I was fortunate enough to work with in our industry -- one, out of six companies, there was only one -- was the most effective, cool coworker I was fortunate enough to know.
It's incredibly easy to point to some science and say "Oh, I'm objective." But I invite you to re-read http://www.paulgraham.com/bias.html carefully, and realize that if what you say is true, then our industry is populated with stellar outliers. That's the definition of bias, right? They have to be stellar to overcome it.
So why would you want argue that the stellar people that managed to get through the gauntlet of discrimination should be looked down upon?