The bottom line here is minors are not making choices when adults are involved in pediphilia. End of story.
The philosophical issue raised is what can be called the democratization of virtue and vice - i.e. if something is [good,bad,neutral] for someone, somewhere, at some point in time, then it's [good,bad,neutral] for everyone, everywhere, at all times. Consequently, no one can even discuss obvious facts (like that not everyone who smokes dies from cancer or heart disease) without being accused of encouraging people to smoke.
The danger with the all or nothing approach is that one only has to find a few counterexamples to invalidate a perfectly useful moral premise.