There's also a large number of folks moving to management as they age. Yes, the tech industry tends to skew young for engineering, but management doesn't. There's also a relatively decent chunk of people retiring in their early 50s (I plan to). There's also a decent number of them leaving to create their own companies, or to join friends at their early stage startups.

I don't think it makes sense to say they're the exception. I'm also mid-40s and have no issues finding employment. Most of my friends are mid 40s/50s and also have no issues. The vast majority of them have switched into management, though. Myself and the other older engineers I know are staff+, though, which helps a lot. I can't imagine being this age as a senior engineer trying to fight an army of equally qualified people in their 20s (who are also having issues finding employment right now).