We all know what he means by dating. Technically fine "dating" is not illegal. But guarantee you that her parents find out he is "dating" her and they call the police.
And if they call the police the police will not be able to do diddly. "Dating," as in seeing each other, holding hands, even going to the movies together is not unlawful between an adult and a minor. As has been previously and repeatedly mentioned, if there is anything sexual or the child is encouraged or aided in disobeying her parents, THEN it is a crime. But, not before.