Looks like the shooter had gun in hand and raising it up while the victim has yet to raise the mace can. IOW’s the first moment of the draw.
The older guy man slapped the trigger puller.
The younger trigger puller escalated by pulling his gun. Why? I do not try to understand the insane.
The older guy was retreating and pulled his mace as a last resort.
Issues: how to defend yourself against a lunatic out for blood or a trophy?
What if they are marching through your neighbourhood at 11PM?