I don't think it really counts as genderbend or sissification.
Your character is definitely male and it doesn't seem like you're compelled to actually turn into a girl? Even the breast growth is avoidable. But I haven't beaten the game yet so maybe I'm missing something.
And as far as sissification its not like people are trying to humiliate the player. I don't know, maybe we have different definitions for those terms.
IMO this game seems like a diamond in the rough so far in the sense that it doesn't use a lot of the typical conventions for these kinds of games.