But that wasn’t the final word that the book gave on the subject.

To present that scene without further commentary goes against the entire point that Avatar: The Promise was making.  

Consider: you’re looking at a comic written by a Chinese-American author (Gene Luen Yang), drawn by two Japanese women (Studio Gurihiru) that primarily illustrate American books, based on an American cartoon that was done in a style reminiscent of Japanese anime (which in turn can be partly traced back to American cartoons), helmed by two Caucasian Americans (Bryan Konietzko and Michael Dante DiMartino), who drew heavily from Inuit, Japanese, Chinese, and Tibetan cultures for inspiration.

The Promise was about Aang trying to clean up the mess left when cultures that had been traditionally separated ended up being mixed (by force), with a particular emphasis on the colonies that the Fire Nation had left in the Earth Kingdom.  His initial instinct was to just try to put things back the way they were and make the Fire Nation citizens leave, but he ultimately he realized that wasn’t possible, because he was dealing with actual people and not abstract concepts.  There were children raised in two cultures, people from different cultures in love, people who had never set foot in the nation they were being told they had to return to in order to make everything neat and tidy.  Aang ultimately rejected the calls to keep every nation/culture separate and instead created Republic City, where people could share and mix their cultures.

As for the Air Nomad Fan Club?

There are absolutely jackasses out there making a mockery of other cultures, or who want to just exploit a culture for profit, discarding it like gum that’s lost its flavor when they can’t get any more money out of it.  But when you go beyond condemning that and decide that only the most dominant cultures can be shared, appreciated, reinterpreted, and spread, then you effectively hand a death sentence to all other cultures. 

Cultural exchange and expansion should be made with respect, empathy, and genuineness, yes, but it cannot be simply shut down point blank. Genuine appreciation and interest needs to be accepted and guided in a positive direction.  The point of The Promise was ultimately that people cannot be neatly put into boxes and told to stick to their own nation and culture. They will make friends, they will fall in love, and cultures will mix, change, and adapt. That’s human nature.

(The OP did touch on some of this in a later post, but it’s worth expanding on)