Had the kid been sighted with a joint and some officer got a whiff of weed, they'd have grabbed his ass immediately.
So the fact that there were confirmed reports of this guy using a range finder out in the open at a presidential candidate rally is inexplicable.
So talking about a failure of comms or someone falling off a roof, or they didn't see a gun until the last moment. We already a mile down the road from where we should have been, and there's no denying that fact.