The point is that if it really were that simple then there'd be no trial. It's possible the law has been misinterpreted by us lay people. We all know what intentional means. It's not a difficult concept to grasp. But to think that it'll be so black and white as to say he shot to kill, regardless of who he thought he was shooting, so he's guilty of intentional murder is naive.
It's not naive, it's South African law. That's why it was included in the criminal complaint.
If a hit man shot the wrong person he would still be guilty of intentional murder.
It's naive for defenders of the psycho killer to believe that he could fire four gunshots at his girlfriend who was using the bathroom and claim a new legal theory - unprovoked, pre-emptive self-defense.