 It's a theory. Dead men don't tell tales. So it's going to be impossible to prove. We can't ask him. We can't go back in time. He's dead. And unless there's some kind of manifesto laying out the plan, we're not going to know. But they're basing it on a number of things. When he used the rangefinder first, he used it from the ground. You're obviously going to get a different range or a different perspective on your target from a roof.