According to the story, they met online when she was 15, and he was in his early 20s. Two years later, when she was 17, they arranged to meet for sex. As far as I know, the age of consent is 16, meaning that a 17 year old can legally agree to have sex with an older person. I don't see how the monitor committed a crime, unless he propositioned her before she turned 16, and that might be difficult to prove in court.
This whole story smacks of a frivolous lawsuit by somebody who just realised that she might be able to embarass a big company into settling rather than face publicity.