Whereas, I loved the scene between Rien + Mallory (who I remember as being more integratedly hermaphroditic)because of Rien's internal comment that the boy-bits weren't a problem, since Mallory smelled female. This resonated very well with my personal experience of how gendered attraction works, and it was really cool to have that reflected, rather than the usual OMG penis! (or vagina) reaction, which tends to leave me scratching my head a little.
I think that perspective is fine, and if Rien at some point had found a woman who could return her love or whom she could make love to, I wouldn't have had a problem with it. But taken together with the other problems in Rien's portrayal, it seemed to me that the idea that Mallory must retain a penis was solely so that Rien would not be making love to someone with female genitalia alone.
I thought Mallory (keep wanting to write Mal, then my brain jumps to Firefly, then my brain explodes a little) retained a penis because Mal's a hermaphrodite, and "I don't love you . . . you shouldn't change yourself for me" ? Unless you mean constructing the character Mallory as a hermaphrodite in the first place - huh. I thought it was just appropriately "not what it seems/contains everything," like his hold.