It's just a matter of what applies where, as you say.
In the -60, it's IFR capable. Not Class A or RVSM stuff, sure, but otherwise yes. The OH-6 and AStar.....even if the guy is instrument/Helicopter rated.......there's some baseline instrument stuff I'd expect him to know that would be applicable, with the knowledge that at the end of the day, he won't be employing any of it for real in
those helos. But if he's holding an instrument rating, he ought to know something generally applicable.
So the extremes are indeed there. The "nice to know" stuff, I like to ask; but mostly as extra credit at the end of an exam, just to see what the guy may know. If he knows it cool, if not, whatever. Things like how an approach is TERPS'd in it's creation....nice to know, not need to know. Mostly interesting stuff is all.
But yes, seriously asking an OH-6 guy about RVSM, is as stupid as asking a UH-60 or CH-47 guy about Cat III ILS requirements. Sure....they all have to do with instrument flying, but are nice to know at best.
I agree with you.