You're leaving out a key point: the shooter was the initial, physical aggressor.I agree. The same rules apply. If someone slaps another, it’s not illegal to draw down on them. And I challenge you to find a case to the contrary. When someone deploys a chemical agent meant to incapacitate, then as long as you can articulate why deadly force is appropriate, it flies. For me, I’m not going to give somebody else the benefit of the doubt that they won’t continue to harm me after my ability to defend myself is diminished.
Further: you are now claiming that it is legal to point a firearm at someone in response to that person merely slapping the other person? Do you really need me to look up, generally, instances of prosecutions for what most jurisdictions call brandishing, at a minimum?
And, as evidenced by the timeline of still photos, the shooter used deadly force before his victim deployed the pepper spray.
So, certainly: if you change the facts, the timeline, and the laws, you can create a scenario in which the shooter was legally justified in using deadly force.