I don't think that Mandy needed much grooming. And I'm not saying that as a character assassination of her along the lines of her being a floozy or gold digger. She was free to do what she did and that doesn't make her a bad person. Some people are ahead of their age and enjoy the company of adults more than of their own peers - I should know because I have a son like that (who always sounded, acted and looked older than he was, his friends would always send him to buy the alcohol
).
For the record: Bill W acted irresponsibly and should have thought a little more about the whole thing. But that doesn't make her automatically a victim. These days, people seem to be forced in either category: victim or perpetrator. Life isn't so simple or black and white. And laws about sexual behavior can only approximate reality at best.
That is actually my one bone of contention with your first reply, Jake (which I knew was coming): You argued that the term "jailbird" (as used by me) already showed that it wasn't "ok" back then. Which means you hold the view that the existence of sexual behavior prohibition laws of a certain time already mirror the bad end (no pun intended) on your (current) moral indignation richter scale.
Some food for thought: Until the late 60ies, even consensual sex between male adults in Germany was considered a crime punishable with prison. There was a law "Section 175 of the Criminal Code". Gay men were commonly referred to as "175ers". Does the existence of that law back then indicate in your view that today sex between men is still wrong as well?
You don't have to deny, I don't believe for a moment you're a gay basher. But the existence of a law per se is no moral indicator. As a German I should know. The Nürnberg Race Laws that paved the way to Auschwitz for German (and other) Jews were an intricate set of laws carefully crafted and passed by an originally democratically elected government. The most hideous things can be passed as law.