Exactly. If he didn’t have an easy access to a fast killing machine, things would have ended differently.
If his friend didn’t get pissed and escalate the situation maybe he wouldn’t have felt the need to shoot him?
I think it was a bad shoot anyways but not because he simply “had the gun on his desk”. He is well within his rights to do that. He is within his rights to hold it. But he messed up at least two times. Saying his friend was going to get shot. Fired a warning shot and possibly entering the house with bad intentions.
On the flip side if he didn’t do any of that stayed at his desk and his friend came and threatened violence it would have been clear self defense.
Part of self defense is deescalation. The last resort is lethal force.