The idea that the default emoji represent white people is ridiculous, since the codepoints are meant to translate directly with Japanese computer systems. In the original NTT DoCoMo set, they didn't even have facial skin (probably because of device resolution and colour limitations), just features like eyes and mouths. Maybe the Unicode consortium made a mistake by specifying them as bright yellow, which people now associate strongly with the Simpsons, where white people are represented as bright saturated yellow.
In my understanding, nobody in the standardization process even considered that Emoji had a race. If people project one race or another onto what are supposed to be disembodied universal facial expressions, then that's their problem.