Quite agree that murder is wrong, but (no matter how it chokes me to say it) Trump was useful, in that he gave this guy a target for whatever was causing his aggression.
(Although planning to kill Trump by flipping a limo with a stolen forklift, then fishing Trump out like a clam from it's shell, with no interference from the Secret Service, is, if not actually 'crazy', certainly wildly optimistic.)
Why do I suspect that if he had bought guns before the arsons, etc, there would have been no impediment to the purchase? Or, maybe someone was on the ball, checked him out and didn't sell him one. Thus, the forklift plan. Because, let's not forget: this could have been way worse.
At least Trump was well-defended, by people who were looking for trouble.
The crowd waiting for Trump, the local schools, this guy's co-workers, the hospitals, etc. might not have fared so well. And, from the link, he was on quite the crime spree: 2 separate fires, and a stolen car.