I do think that holds more water than just "It's old".
However for pretty much any dev I would hire for a job they can get to grips with a technology that's older pretty quickly. Where it does get dicey is when good dev just refuses to work with it. For those devs, I think, when they hold that opinion it typically means one of those other reasons is behind their refusal.
>one of those other reasons is behind their refusal.
I mean, one of those reasons is "When I leave this job will I be able to get another job" is a huge deeply life affecting one.
If you want me to work on COBOL from 1988 then you've limited my work prospects to one of a very few employers in the country at a very specific pay range. If I instead tell you to eat a fat one and go with $language_de_jour the number of employers and potential salary range is much, much larger.