> I frankly don’t care about being on top of tech any more but I’m keen to use my years of experience being productive.

Preach it, brother! :-D

> In this situation would you do it?

FWIW, if it would keep me productive and keep a roof over my head, i'd not at all be averse to working on VMS or a similarly obscure system, provided they didn't require me to know anything about it going in (which would rule me out).

At some point in our lives we have to accept practicality over bling. Let the young'uns fight out the LLM Wars, then walk in (if necessary) once that dust has settled.