This work wasn't done for emoji. They use the same zero-width joiner character [1] that exists to support Indic scripts like Devanagari, and any system that properly handles these languages will also properly handle the emoji.

Yes, this adds a lot of complexity, but it's really a question of whether that complexity is justified in order to support all of the world's languages. And I think many would argue that it is.

[1] https://en.wikipedia.org/wiki/Zero-width_joiner