Anyway, you've misread the warrant application. The forged e-mails were tracked to a dynamic IP address. They searched for anyone else using the same computer name ("bootleg-laptop"), and found that the accused had used the same computer name but NOT the same MAC address six months earlier. They connected the accused to the e-mail by saying that he accessed the same gay social networking site referenced in the forged e-mail before the e-mail was sent, and that the accused and the person who sent the forged e-mails both use Linux.
Anyway, the accused was only targeted because he got into a fight with his roommate, and his overbearing roommate ran off and made crazy accusations about this guy hacking into the grading system. They evidently didn't find anything to support that accusation, so they went after him for this stunt.