Ah... Utena, what did you think would happen if you put the other two out of commission...
Exactly this, I believe.
Wow, we really are not reading the same manga. Utena hates the fact that Magenta has Dark La Verita.
I assume this is some kind of plot to fix Dark LA Verita. Step one is to get Magenta to bust it out, step two is probably something horny, and step three is solving the problem.
Given at Utena instantly going "OH SHIT" the moment she sees magenta is transitioning to La Verita makes me think the point of this whole endeavor was just the usual "Magical Girl Molesting Monday" and not a expected outcome