The same people at the forefront of social justice nowadays would likely be considered unforgivably bigoted had they been raised centuries ago. People end up believing a net sum of their cultural and social influences, even if those influences contradict. It's so easy to imbibe nicely packaged cultural trends that people rarely scrutinize the actual moral makeup of their worldview. This pen-pal likely gathered a progressive and non-racist attitude from the UN's human-rights centered hegemony, and a belief in caste systems from the cultural inertia those old practices still have on Indian society, but never put in the effort to ascertain how those two worldviews contradicted.