Ah, see, I think it's funnier when he can't relate at all, and the song has nothing to do with what we normally imagine as Batman.
Oh, Darien. I had almost forgotten about him.
BECAUSE HE IS SO BLOODY FORGETTABLE! The thing I love most about Mamo-chan is that he is "the Chick." There's, like, absolutely nothing whatsoever to him except being Usagi's destined OTP and the token male in the ten-female main cast. Like being "the boyfriend" was sufficient and they didn't need to actually give him a personality. SWEET DISTAFF JUSTICE!