The store owner needed to control the first( #1 ) assailant completely , because the other ,( #2) robber was still on the loose .
#2 could have easily come back with a gun and or reinforcements .
Owner couldn't safely turn his back on #1 , just cause the punk said " I'm dead ! " .
Plus , owner was smart to keep #1 as a possible meat shield and hostage against further assault .
In my opinion, none of that constitutes "self-defense", nor does it justify continuing to use deadly force while restraining the thief.
Nor do I believe that any of what you posted in the quote constitutes a justifiable use of continual force in any part of the US.
Of course if anyone can show me statutes of justifiable lethal force from any jurisdiction in the US where a defender is legally permitted to hold a criminal as a "meat shield" or as a "hostage", I'd love to read them.
I believe the store owner had readily available options other than holding onto the thief and continuing to stab him. Like, running into the back room from which he initially emerged at the start of the video, and perhaps locking himself in a back room, or bathroom, or heading out a rear access door that shopping mall stores typically have. Is it possible that something bad might have happened if he did that, well, any decision a person makes during a self-defense event can end badly.
Speaking from my experience, when it comes to self-defense and the use of deadly force, I want to use as little force as is necessary to remove myself from the immediate situation and environment. And although attempting to flee has it's risks, so does stabbing a person while restraining them. We each are free to choose our own way, and we must each deal with the consequences of those choices.
Like I said, people can always find a way to justify using MORE force, especially when it's against a scumbag criminal. I prefer to find ways of using less force, so long as I believe I can still safely make my escape, or otherwise survive the situation.
Again, these are just my opinions, and I don't need you to agree with me. Nor is anyone going to change my mind.