Ah yes, Cultural Appropriation.
On it's own, its a very worthwhile topic to discuss. There have been many cultures that have been harmed and even destroyed by others with commercializing and watering down their beliefs and rituals. Good examples are how bastardized Native American culture became thanks to the expansion of the United States, and the Mayan and Aztec cultures being commercialized through the expansion of the Spanish and Portuguese empires. A lot of sacred relics, rituals, and beliefs became nothing more than gas station nick-nacks, pointless festivals, and urban legends.
On the same token, and something these idiots don't see, as a species, the best way for us to understand others from different lands is to understand their language and culture. To share and experience other cultures is the best way to establish common grounds and experience the bond of humanity, that even though we are different we are still the same in that we laugh, cry, rejoice, and mourn. This sharing of culture is what allowed us as a species to be where we are today, in a globalized society where we can conduct business and build relationships with almost anyone is in this world.
What these people are calling for is segregation and sterilization, to have humanity separate and label themselves. Doing so would harm progress, differences would be seen more often, and racism would grow exponentially due to primitive "them vs us" mentality. These people are no worse than those who call interracial dating, "disgusting" or "wrong".
This girl should have just ignored them and moved on, but clearly we can see who the real children are in this matter. The girl was the most mature one in this entire thing.