Pretty sure that's not real...
I don't know if it's a law where he is, but at my schools it was school policy that teachers don't add you on social networking sites while you were still at the school.
I suppose it's to prevent the formation of an un-healthy relationship and also so that teachers don't know all the details of a students private life, to preserve the childs privacy.
I don't think that rule applies for me at College however. But then again, I've hardly asked any of my teachers if they use Steam or Facebook.