He teaches in Virginia, a Right to Work state. He may not be a member of a union since we teachers are not required to be in one.
I'm not in a union either, but stories like this make me rethink my decision all the time. Losing your house is a pretty big risk. I just try to be careful to never, EVER be alone with a child and never, EVER touch one, even a pat on the back to say 'good job' is completely out of the question.
Just sue the school since they knowingly acted as "agent" for the girl and should have known her story was false. Do personal suits against the personnel at the school.
I'd imagine his lawyer has already laid out the gameplan for that for his consideration.