Well I think if you're born in Soviet Russia you're not immediately a bad person, whereas if you sign up to be the leader of a Nazi army then yeah, you're a bad person. If this is the real Cap it suggests the real Cap would be ok being a Nazi if he'd just been born somewhere else. Hydra itself is a terrorist organization that killed thousands of innocents. This Cap has no problem with that. His actions in issue 0 cause the deaths of hundreds. You won't find anything like that in Red Son. And that martin is the point you're missing and why Red Son is this kind of story done right and Secret Empire is this kind of story done wrong. The actions of the character, their heart and soul laid bare, how they behave given the circumstances they find themselves in. Captain America wouldn't do the things this guy is doing, no matter what his upbringing. That's not Steve Rogers.
Overall though I think making someone Soviet or Arab or whatever is innately different from being a Nazi. It's a choice, not a factor of birth. They're different - hugely so. It's like equating someone born in Syria and someone who joins ISIS. And given who Cap is, who created him and all the work done on him, having a story where he's a happily signed member of the Nazi party is a bit of an affront as even a concept. And this story doesn't have the skills on display to make it pay off.