So, we got the first trans character in the manga? Cool! Not cool like "OMG A TRANS CHARACTER BEST MANGA EVER!§§!§3". Just "cool, it's nice to see this subject in a nice manga". The author seems to be a pretty open minded person, so I think the subject won't be treated badly. After all, as he/she say, it's a manga about stereotype and people who don't comply to them.
That aside, there will always be people yelling about this subject or crying "SJW! TUMBLERINA!" or "TRANSPHOBE! DISCRIMINATION!". We can't do anything against that. But, what we can do is trying to talk in a calm an mature way about it. After all, everyone does whatever he want if it doesn't hurt someone else, right? It's not wrong, right?
In short, let's not have a shitstorm in the comment, okay? It's a nice manga (not perfect but nice) and it's trying to talk about a subject which is not good or bad. So let's just see how it will plays out, ok?