I'm gonna be lazy and C & P what I posted on CU:
Yeeeaaaaaaahhhh ... I doubt this happened. Because that just doesn't sound like how a young child would express themselves. Because visitors to Hawaii would see people of various skin colors pretty much from the moment they set foot in Hawaii, and more likely before boarding their flight to Hawaii ... or while walking through that mainland airport ... or in their everyday lives. It's just too implausible that these girls had never in their lives seen a black or a dark-skinned Hispanic or a Native American or a person of East or South Asian heritage or a Polynesian.
That said, what would this DUpipos post have been had those parents come down on their child in a public place? I'm sure there are a good number of such DU-posts about the horrors of parents correcting their children in public. Speaking personally, had I said such a thing in public, my parents' reaction most likely would have been, "Shush. We'll talk about this at home!" Quietly, so as not to create a scene, but with a voice tone that would let me know I should shut up. And we would have had the talk.
My real life from my earliest years, though, was seeing my parents interact with people of various skin colors as people, and hearing them speak of people with Hispanic, Chinese, and Japanese family names as friends, classmates, and people with whom they socialized and/or did business. We didn't have a "race talk" until I saw MLK on TV (early 60s) and wondered what was going on. When they explained, I thought racism stupid and said as much. I didn't see it, but I suspect they saw success in what I said.