Technically gender bender is about bending the rules of gender, girls acting or dressing like guys and vise versa. so your story fits, even if the stories i read were more gender swap i still enjoy a good traditional gender bender and well, femboys exist in my own story. So I'm never going to complain if we get a little more of that.In my story I wrote a quick chapter about gender bending, well... not exactly, an evil character was transformed into a femboy and every time he tried to reveal his identity his body felt the urge to sleep with other men. Unfortunately some readers didn't like it but it gave me the idea of creating a separate story with this premise.
It's really a good topic
Almost the same, I started at Wn as a reader and most of it was garbage too. Some of it hurt my head to read and I had to make an effort to understand. That was one of the reasons I startedAlmost same, started
We are free to say what we want as well as free to listen to criticism. If you have something to say, you can say it, I don't see a problem.
As for your villain becoming a femboy and having a change of desires is a fun topic to explore and even expand on. Does he dip his toes in or fight like his left arm is trying to kill him? Does he get addicted to it, gain a new perspective on himself or gender? Does he try to influence others with his new appearance or even experiment by turning others into femboys or women?
And that's ignoring what the supposed heroes are going to do or feel about it. You can play a lot with both male and female povs.
As for your readers not liking it, well you can't always get people to enjoy soda over tea. But you're already considering or making a new story so you'll find people to read it.