The details of this are very vague. Late teens could be 18 or 19. This also apparently happened some time ago. In addition, it didn't say that this girl was an employee -- the article just said that she had met Greene through the column. I imagine that most people Bob Greene, or any columnist for that matter, meet in their lives are due to their column.
I also remember reading that Greene was friends with Bush 41, and that he had written several columns in his defense. Is this payback? I don't know. It just seems a bit odd that, unless significant details are being left out here, that a columnist would be forced out for something in his private life.
It seems like a tragic mistake, but we all make choices in our lives that have consequences both good and bad. Hope he lands on his feet somewhere for another chance.