So what? Nobody claimed that they can't. If you can't learn a programming language, you're not a programmer. I'm 47 myself and learned Go in a week or so (7 years ago). What I wrote is that they won't, in my experience as CEO/CTO I've had enough people who used "the one true language" for 20+ years and outright refused to touch anything else. This emotional attachment to languages (or, more recently, frameworks) and the fact that you get away with it too often (there's always another job for your favourite language) is what makes hiring difficult and different. Imagine a car mechanic who refuses to repair a BMW...

Sorry, your statement came across a little differently than it seems you intended. But I also disagree with your idea here - I've found stubbornness in young people and openness in older people as often as the reverse. If someone is interviewing for a job in your stack though, you should assume they aren't going to come in and say "guess what, I'm only writing C".