That's not an argument at all. You could insert any crime into that statement...

"If it's not worth your life, then don't commit vehicle registration fraud."

Only if you deliberately ignore the plain distinction between vehicle registration fraud and stealing a person's stuff.

What is your threshold at which killing a non-violent thief should be allowed?

If I catch someone stealing my car from my driveway at night, can I shoot them as they try to start the ignition?

If I see someone swiping my cell phone off my restaurant table while I'm turned around... shoot them?

What about my umbrella?

My opinion would be at the point when a reasonable person would fear for their life.

For instance, if I own a vehicle and it is my primary method of escape, and someone starts fucking with critical systems like say the exhaust with a sawzall, I woud definitely start fearing for my life and the life of my family. Particularly when automobile is absolutely critical for survival, access to grocery/medical care etc, escape from say criminals in your yard operating sawzalls in commission of felonies, in much of America. If someone is in my yard fucking with my way to get away in danger, and they're physically tearing it apart with a sawzall, then I think it would be reasonable to allow defense of my family.

If someone is just stealing a hood ornament with their hands, then no maybe it's unreasonable to fear for your life.

With a phone I think it would depend more on context. Intentionally and without consent stealing / disabling someone's method of calling for help and emergency could make a reasonable person fear for their life if that person was also in the process of commission of felonies in your immediate proximity with a dangerous sawzall.

Then perhaps the punishment for every crime and infraction should be summary execution. Blow a stop sign? Execution. Over the speed limit? Execution. Stole an apple from the grocery store? Execution. Sounds like a perfect society?

Don't be ridiculous, there's nothing perfect about a society like that.

When you infringe on the rights of another human being, you put yourself at their mercy. Some people are not very reasonable. Legal or illegal, you just might find yourself attacked by that person, possibly killed. Even if you make laws against it, there's always that danger. Every time you violate the rights of another person you're risking your life, and it doesn't matter what the law says.

Uninvited fucking with critical systems of someone's primary method of transit/escape/transportation to medical care/grocery etc, especially with a sawzall under the body of the vehicle, causes a reasonable person to fear for their life.