This is not a binary in my mind, it’s kind of a spectrum. The guy standing between me and the door when I decide it’s time for me to leave is definitely on the chopping block, but also there’s some aiding-and-abetting that must be considered. Maybe that guy has the key to the door, but someone else just chained me to a pipe once I was already in the locked room, and I’m afraid that someone else is in the line of fire too. And maybe there’s a third guy who did the actual kidnapping but didn’t contribute to chaining me up or locking me in, if the opportunity presents I would give some pretty serious thought to putting him on the list as well. And so on. There’s a point at which it is no longer reasonable of course; the guy who drove the van I was kidnapped in but otherwise didn’t participate is probably safe, for example. But also we can get into credible non-direct or non-immediate threats, as you say: the guy who killed 15 teenage girls is sitting in his van in front of your house watching your teenage daughter, are you just gonna lock the door at night and hope he finds someone else? I agree that that’s debatable, but my overall point here is that the lines aren’t nearly as clear as you make them out to be.

Now personally nothing would make me happier than to live out the rest of my life without having to even threaten anyone else’s, for obvious (and some not-so-obvious) reasons, but there’s a line somewhere that if crossed could convince me to reluctantly set that deeply sincere hope aside temporarily.

To me, you’ve moved beyond arguable necessity and into opinion

All morality is opinion; there is no objective moral truth, so this was always a matter of opinion. The fact that you don’t recognize that is kind of concerning to me, it suggests that you believe there is an absolute moral truth, and folks who believe that sort of thing tend to have some pretty kooky ideas about individual agency and shit. Moral certainty is the currency of zealots, and it’s hard to imagine anyone who has done more harm than those zealots who are utterly certain that they’re right (or, worse, that they have some deity on their side.)