I am in my mid-60s and I don't feel like I have suffered any age bias either at large companies like Google or small startups I have helped. I sort of grew up with computers. My older brother and I got a mini version of a mechanical difference engine when I was a kid. When I was about 11 my Dad got me occasional use of a time sharing system, so that planted some desire in my brain for using computers. In high school…
I've noticed that whether you are/were interested in management is a factor. Younger managers can imagine hiring older managers, but rarely engineers.
I have never had to do it, but I'd like to think the 60-year old version of me would be much better at my job than I am. Thus, if I hire them, I'd wonder "why am I tech lead? It really should be the other way around".