I think this case won't see the inside of a courtroom. It's a gross misuse of the statute in question. I'd be willing to be the prosecutor has a reason for pushing for charges. Also this would presumably apply to any email account - adult kids, parents, brothers, sisters. Snooping is bad for a host of reasons (but I understand necessary at times) I don't think the fear of a felony would stop anyone nor is it the best us of a courts resources.
Patience is bitter, but its fruit is sweet. --Jean Jacques Rousseau.