To me, this seems like harassment, worthy of a slap on the wrist. If he does it again, take away his computer privileges or something. But prison time? You have to be kidding me.
He was the author of an email threatening to kill the vice-president -- he is responsible for 'uttering' the words. In many jurisdictions that is the complete crime (strict liability).
Furthermore he aimed to pervert the course of justice by framing someone else.
Both these crimes are considered serious pretty much everywhere. Judges tend to look unflatteringly on perversion in particular.
(IANAL, TINLA).
Had his plan succeeded, the victim would be in prison for the rest of his life on the combination of kiddie porn and threatening the vice president. That's way beyond "harassment".
> The subject line of one e-mail read: “This is a terrorist threat! Take this seriously.” “I swear to God I’m going to kill you!,” part of the message to Biden said.
Not sure why you think he didn't threaten to kill. Seems he was found guilty.