Those people were wrong.
This isn't some kind of "oh morality is relative and somethings are cultural", it's just objectively wrong, regardless of who or how many people claim to like it.
In your individual opinion. In mine, too, and hopefully everyone else’s here. But the OP was clearly talking about what views are presented as “morally right” by normative social forces, and those clearly differ across time and place, often as political power waxes and wanes.
And even now we see that the normalization of naziism is apparently impossible - I was incredibly cynical about the American right wing happily embracing naziism, but I guess I was partially wrong: there's a schism this week over popular American right wing media figures platforming the nazi Nick Fuentes.
Before modernity, extraordinary violence and propaganda were, well, ordinary. Hitler just made that work on industrial scale, but the underlying moral ideas weren't anything new. During antiquity, people didn't mind slaughtering entire cities. Even more modern history is full shit like that, look up Mongol invasions.
BTW don't you think that it's a little awkward that in modern times "pirates", which were people that'd literally kill seamen for profit, are considered a fun Halloween theme for children? I can imagine that in 500 years Nazi costumes will be similarly normalized.
This is why posting about how “Nazism is objectively immoral, m’kay?" misses the point and can be counterproductive. The whole reason that fascism is a continual spectre is that, it turns out, by appealing to people’s base instincts and cracking heads, a malevolent political form can completely sidestep morality and institute the society it wants to see.
