Settin up a shot like this, ya has to know when the Target is going to be there and pretty much exactly where he will be standing. Ya also need to know from whence the aforementioned can be seen (targeted) and exactly when it would be available. What Im saying here is that this dude didn't just fall off a turnip truck in front of this building and climb up to see what was going on. He had help. Same as Lee Harvey Oswald. Maybe this guy was a lone wolf who managed this on his own but I fricken doubt it.
Liberals are like a "Slinky". Totally useless, but somehow ya can't help but smile when you see one tumble down a flight of stairs!