You know you have a bad take when even a theist has to step in to point out exactly how dumb you make yourself and this entire community look when you say you think morality/ethics are objective, man alive.
This is just patently false on every conceivable level. Cultures define their own morality, laws, ethics, and they vary WILDLY across the globe and NOBODY has anything anywhere CLOSE to proof of divine right or authority to assert that the values of the culture they live in/fight for are universally true and correct, full stop. Anything short of this is going full mask-off advocating for their personal culture being in every way superior/correct/divine and "their people" being the chosen people of some higher power, you know in other words, fundamental religious terrorist shit. Feel free to push back if this is the hill you want to die on go right ahead, the local three-letter-agency monitor would, I'm SURE be happy to add it to the pile of evidence that this place harbors dangerous and mentally unstable extremists.
If you believe otherwise then you seriously need either a proper education, therapy, or public humiliation, and in Pundit's case all three are DESPERATELY in order, all offense meant.
This is basically an argument that because something exists, therefore it is good, or at least morally neutral. It fundamentally does not understand how ethical arguments work.
I admire Japanese culture quite a bit, but Shintoism is fundamentally a religion which values honor and denies human life as being special. That is a really bad combination. This is why the 47 samurai are a national myth of Japan, but it's also the reason Japan resorted to kamikazi tactics in World War II and to this day can't look its own past war crimes in the face.
By the reverse token, American public schools often proclaim the victimized status of Native Americans. And that definitely was true to some extent. But it's also true that horses are native to North America and that Native Americans hunted horses to extinction. They had to be reintroduced by Europeans. Native Americans also had technologically stalled at late stone-age and while their armed conflicts with each other were rarely (directly) fatal, they usually resulted in the losing tribe being banished from good hunting, fishing, or farming grounds and starving. In terms of pre-Columbian American history, the Trail of Tears is not that special; it's only historically remarkably because a lot of tribes were shoved together...and because it was done by a white guy (Andrew Jackson). The European-descended colonists typically tried to do better and do regret it today. A Native American tribe displacing another tribe would not have tried to do better and would never have regretted it.
My point is that cultures are by their nature hypocritical and terrible sources of moral values. I am not saying that culture has no value, but that in a good situation morality and culture are at right angles to each other, and often outright conflict.
The bolded words demonstrate that you're using your own particular moral framework to judge another culture's ethics as being "bad" or "good" or "worse" or "better". The Japanese soldier in WW II or Comanche in the 19th century aren't likely to agree with your assessment. Your culture doesn't rest in some kind of authoritative space that renders it an objective standard to which all other standards of right and wrong can be measured...well,
you might consider it 'objective', but I'm sure the Japanese and the Comanche would view their own the same way.
The question is if there is a standard outside of culture--a divine (or even natural) source of "moral law"--'laws' that differ from natural law in that they can be defied and there are no immediate consequences for doing so. I accept a standard rooted in a particular theistic view that others might view as simply the cultural product of seventh-century Arabia...just as I might not accept any reality behind the Shinto gods and godesses outside of Japanese culture.
Cultures might be 'terrible' sources of morality, but every single moral standard that we have exists embedded in a particular culture. The Quran, the Bible, Kant, Hegel, Nietzsche, Marx, Genghis Khan--they all arose from a particular cultural milieu. Modern moral philosophers may be aware of more historical examples of various systems than others, and might even render some judgment on the ability of various moral systems to deliver what they promise...but calling one system 'better' or 'worse' is really just revealing that thinker's opinion (which is likely heavily influenced by and formed in their own cultural experience.) Of course, I think my viewpoint's right and in alignment with the Creator of the Cosmos...but others can and do disagree.
As for the naturalistic fallacy--yes, that can happen,
if one says "I can't judge any cultural standard of right and wrong as "good" or "evil" because whatever is, is good (a la Alexander Pope). No; it's entirely possible for one to judge the moral goodness of another culture or of one's actions based upon some standard--their own standard, your standard, a philosophical framework (e.g., consequentialism). That doesn't change the fact that actions we might consider "evil" exist. That's a given. Nature (or Nature's God) permit their existence...which of course leads to the age-old question "the problem of evil" which theistically has been addressed countless times (though not everyone agrees on the solution, even proposed by their co-religionists.
And FWIW, I think judging Native American morality on what their ancestors did to horses 10,000 years ago is a bit weird--like judging modern European moral standards based upon the bones found in Europe that indicate some early Europeans were cannibalistic. Heck, we don't even judge Germans of today for crimes done less than a century ago.