Why is a gun appropriate for the task and a grenade not?

A grenade (frag not flash) is laughably excessive.

So if someone says “I am going to murder you, I am going to strangle you until your eyes pop out”, you don’t believe that there’s a right to pre-emptive self defense?

Anyone can say what they want. My response to a statement like that would be a restraining order not a gunshot. I don’t accept preemptive as self defense at all. What am I defending against? Harsh words? Guy says that and reaches for my throat for real and it’s a battle.