Justice should be blind and should not care about 'social harm'. At various points in time, social harm was being atheist, being jew, being gay, having money, e.g. Turing was sentenced because him being gay would do social harm. Once justice starts looking for some other reasons except what the case is, justice is no more. IF there are laws for underage perjury, there should be some consequences, slap on the wrist, public disapproval, instead, they continue to call her victim.
If you're arguing justice should be social engineering scheme instead, well, that's whole different topic. There are plenty of countries who adhere to this point of view, United States was not supposed to be among them...