Agreed, I thought that was an excellent account from @DinoR. The law generally seems to be perfectly in accord with common sense, not reliant on rigid technicalities that set up “gotcha” scenarios.
Yes, it seems to me that the assailant in the OP’s hypothetical has created a situation where he has a strong burden to prove that he is no longer a threat. After throwing one grenade, if he is merely continuing to stand in the vicinity any reasonable person would surely see him as extremely threatening. Under these circumstances, it’s hard to imagine how he could meet the burden of demonstrating that he is no longer a threat other than by leaving quickly enough that the question of shooting him is rendered moot.
“Gotcha” scenarios highlight the weakness of the argument. If you can say the “gotcha” is something so remote like, say, someone threw a hand grenade at you (outside of a battlefield) and you lived can you shoot them then maybe you’re right. Or, we can come back to earth and wonder what happens in a bar fight which is a common(ish) occurrence?
What is common sense after someone was shot and you are in court? I can conjure a million, “I was afraid for my life” scenarios. Which rise to letting me use lethal force as a court would see it?
The first person it is up to is you. You need to have a reasonable argument based on observations and local law that you are at risk of severe bodily harm or death and lesser force is inadequate. You need to be prepared to make that argument after the fact. The prosecutor and, if it gets that far, the jury will assess your argument. Still the first step is internal. You should be able to make that argument to yourself before you act. None of the bar fights I have seen or had someone try to start with me came close to that high bar.
If you have not mentally prepared to make those tough decision under stress about deadly force, it is a bad idea to choose to carry the means to use that force IMO.
Since those decisions are hard to make under the influence, it is generally either to illegal to carry in bars or only allowed if the person carrying is not drinking. Your argument for deadly force is going to be a lot shittier when the first crime of the night was you carrying a gun illegally.
“That guy was coming at me intending to harm me! How did I know if he’d stop at a punch to the nose or go further and break my neck?”
I am not persuaded that states that have stand-your-ground laws will discern the situation. A person intending to harm you, in any fashion, is sufficient reason to kill them.
Gunning a man down to avoid a fair fight would have at least one Texas juror voting that it was murder. If there’s two or three of them and its dark? Well, may they rest in peace.