I figure they can't be entirely human, or they'd just plain die trying to walk from one shelter to the next -- the bit with the 4th-kalpa manikins and the Afterlife Bell sort of clinched that one for me. The manikin rang the bell, became human, and was instantly destroyed by the light of Kagutsuchi. SUCKS TO BE HIM.
but yeah, also the lack of powers. Poor things. I sometimes wonder if the extremism of both of their Reasons isn't actually a way of saying "NO MOAR DEMON COCK PLS." ^^;;