If we're on the point that IGA is sexist, I wouldn't call him anymore sexist than any of the previous developers in the past.
And in Rondo, you play as a pink dress wearing 12 year old magical girl with more than your average bust. I think her design alone is pretty sexist. Don't forget her ending where the shot is angled where she has to cover what's under her dress. Sonia's a woman who's just there to say "See? We made a game with a woman in it!" And her game sucks.
I wouldn't really get pissy on IGA for sexism if I don't get pissy about the previous heroines. I mean even Charlotte's design is only as sexist as RoB Maria's, barring how some people find her useless in gameplay. Plus, IGA specifically searched out for Ayami Kojima, a female artist, and because of that, the franchise actually got a handful of female fans. And he has a pretty wild beard so that makes everything okay.
Also, I wanna argue that Shanoa's deeds were still heroic and that she didn't fail because the heroic value of her deeds don't suddenly diminish just because no one knew about. And I actually prefer that she couldn't save everyone instead of pulling out some Mary Sue trick but nagger.
Edit: On second thought, maybe Charlotte is worse than Maria with that thing she does when you hold up.