What mitigates against the lone nut patsy angle here is that there's no backstory to suggest the kid is a nut. The CIA would have had him looking up 'how to whack the president' or something on his computer, had him seen with some handlers doing some crazy weird shit that would stick in witnesses' minds. Or something that would support the lone nut theory. Here, there's nothing beyond he was a nerdy kid who liked guns, which describes probably 20% of American youth.


On the security side of things, the SS goes to these venues weeks in advance and scouts them out. They figure out all the dangerous spots, and brief the local cops to cover them. Then the day of the event, they go there in advance, make sure everyone knows where they're supposed to be, then before they let the protectee anywhere near the place, make sure everyone is where they're supposed to be. They wouldn't let Trump get out of the car before everything was perfect. This time, there's a glaring hole in their security. You have to wonder why.