Play stupid games, win stupid prizes, don't chase a man carrying a rifle when he's trying to run off.
... before events even got that far;
Don't travel to a neighbouring state in an attempt to police activities over which you have no jurisdiction.
Don't take a weapon into a crowded scene in an attempt to give you authority over people who significantly outnumber you.
Any reasonable adult would conclude that his actions in this regard were reckless and provocative. He wasn't casually open-carrying, he took his weapon to the scene with intent. He could have gone there without it, but did not. (EDIT He could have taken a shield, goggles, other protective gear with which to defend himself, but he did not. He took an offensive weapon, and not much else. Further EDIT - it's a stretch to claim self-defence when you are the one with the offensive weapon, taking up a combative stance toward those who are unarmed...)
The reason he was running from protesters is either the protesters' response to his first shooting, or protesters not wanting to die from his recklessness, and seeking to disarm him.
Of course, events would not have got to this if the country had significant gun control laws ...
Also, the discussion would be moot if the officer involved with Jacob Blake had not shot him in the back seven times. All his fault. If only we could dock his wages and pension to pay for all the damage ....
EDIT - in a cruel twist of fate, it's reported that one of those killed by the armed 17-year old was a friend of Jacob Blake's ...