Well, he's knowingly misrepresenting himself. He's sending email as Dustin, with the specific intent of gaining unauthorized access to a system. (and he knows he's not authorized to post on Dustin's posterous)
IANAL, and it's not exactly the same circumstances, but when Sarah Palin's e-mail was hacked during the 2008 U.S. presidential campaign, the FBI and Secret Service both "got involved". According to Wikipedia the hacker in question was eventually found guilty of (1) felony obstruction of justice by destruction of records and (2) misdemeanor unauthorized access to a computer.
The parent has a lot of upvotes, so I really want to know why they agree he committed a crime, rather than found a bug.