The guy's a liberal putz but he didn't directly threaten the president.
"....I wouldnt mind seeing him dead...." does not sound like a threat.
Sounds more like a liberal professor running off at the mouth, which is what they do.
The SS won't take this guy seriously enough to talk with him.
The threshold for this kind of talk has dropped a bit due to the terrorist threat and he is going to get grief for this.