Well, Imitatio clearly knows jack and shit about psychology, and Utena's in particular. Utena is literally willing to let herself be a stepping stone for magical girls to rise up; it's only due to Venalita she went berserk. At heart, despite being kinky, Utena's a good person, and Imitatio can't seem to understand that.
That said, funny how her power is "potions" AKA messing with endorphins and sensation play. Yet another aspect of BDSM.