In my non-legal view of all of this, the federal treatment of this issue is that a child is a minor until they are 18 years old and this is a crime. Here's some interesting links. Bottom line, the moral equivalence BS in this and the earlier thread is a smokescreen. Regardless of political affiliation, this kind of behavior is unacceptable.
http://www.law.cornell.edu/uscode/html/uscode18/usc_sec_18_00002251----000-.html
Definition of a minor:
http://www4.law.cornell.edu/uscode/html/uscode18/usc_sec_18_00002256----000-.html
http://www.whitehouse.gov/news/releases/2006/07/20060727-7.html