I agree with you except for the part about the economy. I think they want to confiscate guns, period.
I think the left, the really radical extreme left, may very well have operatives who find and befriend people like this guy and quietly inflame them to anger and put the idea in their heads, then this “friend” disappears. After the guy does go on a shooting spree they are the first to call for total disarming of the citizens.
People will call us nuts but these things seem sooo conveniently timed. If my memory serves me, there were more of these shootings under Clinton and Obama than there were under either Bush.