If you hit Donald Trump with any sniper rifle calibre from 150 m distance ANYWHERE on his body, the man's toast. He's a 80 year old jellybean, held together by his personal BigMac/Adrenochrome mix.
But the dude likely played too much COD or CS and simply got convinced that Trump has too much HP and you need to go for the headshot. Motherfucking 
I don't know anything about this kind of stuff but surely it wouldn't kill him if it hit his shoulder or something, right?
At his age? And at his level of physical and mental fitness? Shock alone can kill and getting shot is pretty shocking, no matter where
Really depends, in the shoulder he's probably surviving but not in a good way for years, maybe the rest of his life. Just the wrong tools were employed for a high chance of success at that range.
shoulders have a lot of arteries, but bullets are small and there are plenty of places to be shot that won't kill you. you pretty much want to aim for the heart, lungs, and/or central nervous system to ensure the target is down.