I will give you my take on this.
The wound Mr. Kirk suffered was an assassin’s wound. The bullet severed the jugular vein. There is no rescuing that. Holding pressure isn’t going to do much good. It is a large vein that drains deoxygenated blood from the head, brain, and face. It was a fatal shot.
That shot, unless it was a lucky chance by an amateur, was carried out by a marksman. The knowledge of anatomy enters the picture. That is not a kid with ideas. That is a practiced marksman.
My question is why would anyone want to kill the guy? He was a wiseass Republican with dictatorial discourse that young Republicans found entertaining. They tried to mimic him because he made money at it. My best guess is that someone was jealous of him. Not for his wife, but, for his success. Who would be so jealous of him stealing the Republican limelight his death would be desirable to hire an assassin? I am not convinced it was a rooftop. It was a precision shot.