As a POC mod of c/vegan, I approve of it because I'm wholly aware of the angle of where this kind of comment regarding carnist takes on culture comes from. It comes from people refuting a red herring that vegans inevitably end up having to address due to some carnists on the left having bad faith complaints about vegan advocacy.

Vegans are not, unprompted, going after any particular culture for being carnistic. It wouldn't make any sense because every single culture throughout history, including Western European ones, has been carnistic to some degree. However, some people from cultures in Africa, India, etc., on average, consume fewer animal products than those in western countries, but there has never been a society that has upheld veganism as a universal, strong core tenet that's practically inherent to their society, in which they see animal exploitation as unequivocally wrong and to be condemned at all times.

For this reason, a lot of carnists who divert to takes such as "What about this culture that's heavy on meat consumption?" and the like are being entirely disingenuous. Many of these carnists, but not all of them, are white people, so they're literally exploiting a non-white culture as their own excuse for not going vegan. In addition, speaking from my own experience, a lot of carnists who do this neglect the voices of principled vegans of color, and they are just going for an extreme reach at painting veganism as reactionary so they can feel as if it's not at odds with their leftism for them to be carnists.

Ultimately, being historically marginalized does not justify oppressing others yourself. Just as one would say Zionism isn't justified due to antisemitism, TERFism isn't justified due to misogyny, and transmedicalism isn't justified due to transphobia, human supremacy isn't justified just because a group of people has endured colonialism. There are also literal Indigenous people and people in post-colonialist states who agree with this, but they often get neglected.

I'm not critical of identity politics inherently obviously, but when you have a subject that gets as much disingenuous concern trolling as veganism, it seems like people redirect to these absurd accusations of racism and colonialism just for the sake of making veganism baselessly sound more malevolent than it actually is. For this reason, I do not give it a pass as a valid complaint.

That being said, it absolutely is possible for a vegan to be culturally insensitive, racist, or have a colonialist mindset, but I do not believe that saying "Culture does not justify carnism" is what necessarily indulges in such a mindset at all.