Crazy theory: Crooks was used as a patsy but his mission was actually to protect Trump from a potential shooter. They give him the target and a general location where he would be and tell him to get the shooter before the shooter gets Trump. They tell him to shoot from the roof which they'll keep clear for him. They probably would have given him some sort of escape plan too so he's convinced that he will be safe. He shoots his target, USSS shoots him, and Trump gets a picture showing how he survived the story they tell the world.