As a current law student who is passionate about criminal law, I hope my response sheds some light on statutory rape law. Statutory rape is a strict liability offense. Strict liability means that the intent aspect is irrelevant. As such, any question of a consent is out of the picture. Whether a minor is "consenting" or "willing" to participate in a sexual encounter is out of scope. And that is by design. Strict liability offenses are designed to make it easier to prosecute in otherwise complicated areas of law. Because an essential element of rape is consent, and a minor is not legally able to distinguishing between "knowing" and "appreciating", a minor's consent is made irrelevant in statutory rape law. It makes sense because minors don't have the life experiences of an adult and are more easily manipulated into situations that they may be harmed easily. Law is always made keeping in mind the broader public policy implications, rather than a few individuals who may be an exception to the rule. I strongly agree with statutory rape laws. It is not about the age difference, it is about protecting the interests of a minor who is mentally immature to consent.
Edit: I think he got off easy at 6 years. He should have gotten the full sentence of statutory rape in his state.
Just out of interest - studied law myself but not US based. Do the circumstances make a difference in the verdict? A 30 year old coercing a 14 year old into having sex and actually rape her against her will vs. a 30 year old in a consensual relationship with a 14 year old.