Just thinking aloud here; why does Ritsuko actually want Ryo dressing up and acting as a girl? I've seen in some pictures, she sort of treats the poor guy as her plaything. 
Ricchan uses him as a testbed (harhar) for her research.
Like what makes an idol favorable to the general public? What kind of image should an idol have to sell well?
Typical Ritsuko stuff really.
From Ritsuko's point of view, (apart from the sadistic fun of screwing over the perceived gender of an adolescent boy), it was only natural for her to "create" Ryo as a cute, fluffy female idol, since they are the market standard, and they are what sells the most.
Ritsuko doesn't do that herself, since she's purposely aiming for the niche crowd.
