Morgan, I can't believe you - of all people - are defending this principal's actions. I thought you'd be the first to join me in stating that this is wrong.
Who's to say that little Billy's mother isn't having an affair with Jenny's dad? Who's to say that Chris's father isn't an alcoholic? You cannot reject a child, just because their parents are doing something horrible! The child has nothing to do with what the parents are doing. For all we know, this little girl disagrees with what her "parents" are doing, but she loves them anyway, because they're the ones who are raising her.