It wasn't a bad analogy, it was a disingenuous interpretation by other readers, like you. That or, just really ignorant of the relevant history, such as who the Waffen SS were....

So if people want to play the "what about the good Nazi" game with it, then fine, we can skip straight to the source material and inspiration for the Fire Nation: the Japanese Empire.

But again, I don't believe art has to directly reflect reality. So I don't consider this cartoon to be a war criminal, but if people insist interpreting it as a direct reflection of reality, then yes, an IJA General would be his historical analog.