I really hate that people that are sufficiently old enough just get a pass from a large part of society because "they're a product of their time". Well they're living in my time now, and I will judge them by the standards of my time.
I think it's wrong to decline a person from a job or from a loan just because they're old, but if that's the standard then it seems to me that I should judge them like I would anyone else. If my grandmother wants to insult Mexicans and call them all "lazy and living off the system" in front of my Mexican immigrant wife [1], she's of course allowed to say that but I don't feel even a modicum of guilt for calling her a nut or an idiot in the process.
Whether or not it happens to me is irrelevant. I would hope that future generations hold me to the standard of their time while they and I are living concurrently.
[1] Actual quote.
If you're alive and not in a mental institution today, then I don't feel bad judging you by the same standards as everyone else. If an 80 year old says something racist or sexist, I really don't care if that stuff was acceptable when they were 15: it's not acceptable now.
Based on what you described of your parents, I wouldn't call them nuts just based on that.
ETA:
I'd like to clarify a bit; even though I don't agree with your parents in this example, and I think they're wrong, being wrong doesn't imply "nut".
I guess I view it as a matter of degree. I think overt racism is way worse than being a bit wrong about what minimum wage should be, and while, as I said, I don't have a strict line, the line does more or less exist.
My other grandmother is the same age as my idiot grandmother, and yet she's managed to somehow not be really racist around my wife. I guess I don't know for sure what's in her brain, but at least outwardly I wouldn't classify her as a racist, so please don't misinterpret what I say: being old doesn't inherently make you a nut.
If a young person says something dumb or offense, it's perfectly fine in my mind to hold them to the same standard.
They're nutty. Other older people manage to understand the value of things and wages in the world now in comparison to when they were younger. I'm only in my 40s, I get surprised by changes since I was in my 20s, but each surprise is an update.
It's supportable to say that you strongly disagree with someone's worldview, but that alone doesn't make them a nut.