It always happens. When violent acts are committed in the name of some political belief or another, the target side blames rhetorical incitement from the other side; while the presumed originating side claims the violent are singular people, in no way a result of hate speech, and, as a matter of fact, the target side is the one to blame. They were asking for it, we'll be told.
I'd say the same about the guy that actually threatened Eric Cantor (as opposed to the imaginary attack over which he was so breathless a few days back):
He evidently does hear voices. Much as the RWS™ will try to push him off as a liberal, he's way too crazy for that. Screamer, all the way. Got the paranoia and the theories. Religious nutjob? Not many on the left.