What would you do, if you were in his place? Imagine, you have to train several months in a world without anyone you can speak to, would you be as immoral as he is?
Pesonally, I think everyone who crosses the moral boundary with even only the smallest step (looking at panties), would start to rape at one point. I also think that so men could stop himself doing these things. I don't say this manga should insert it, I don't need it, but I wonder if others had the same idea about moral and the human nature.