Uhh... Buddy.... pal... Did you forget Toph is 12 aka a loli and book 2 had incest , so both are definitely not out of character for the dev.
Also with all the positive feedback from the possible Jinora content I would be pretty surprised if the dev didn't capitalize on it.
Check again friend, he specifically states he aged all the girls in the previous books who were underage to 18 and over so as to not have underage content. Toph was not 12 in Book 3, she was 18. Just because the art doesn't change, the age did. Jinora might be older, but so far it has not been stated that her age has changed at all, so she'd still be about 11-12 and therefore would not be used for sexual content. Actually go back and replay the game, the aging up started with Katarra back in Book 1.
Also, the "incest" was only in the context that they were both there, they did not in fact actually perform sexual acts on each other, which is more of what constitutes incest content in Patreon's eyes. It was more like she helped you fuck her mother.
So I don't know why you're expecting to have incest with a 12 year old when there is no way Patreon would let Mity get away with it, nor has Mity ever done anything to make you expect it. The protein shake and the "letting the crush continue" things were funny and a little pervy, but they weren't "strip her down and having your way with her" bad like you've done with Korra, Pema and Lin. In fact, even the MC has a problem with doing stuff to her on the slave route, so clearly he has some morals, even if they are fubar.