It is obviously American doctrine to try and kill the enemies President.
Brave American bomber pilots dropped bombs on Libyan President Muammar Qaddafi's house in the middle of the night trying to kill him.
Brave American bomber pilots bombed all of Iraqi President Saddam Hussein's houses, trying to kill him.
They were unsuccessful.
If an American were to single-handedly kill our enemies President, he would be considered a hero.
Booth did that.