Unkillable Settlers?

When you assign a settler to be a provisioner, they become "essential", they cannot be killed by another NPC other than you. Just like a companion. They may get knocked down but not killed.

So what if you assigned all you settlers to be provisioners but then immediately reassigned them to other tasks like farming or defense? Either it's a bug or feature but once an NPC is assigned to be a provisioner their name becomes "Provisioner" and even if you reassigning them they stay a "Provisioner".  Yes, they still maintain their essential quality.

I tested this out. I shot, but didn't kill, a "Provisioner" that had been reassigned to defense. My companion, MacCready, "killed" the NPC but in a few seconds he got back up again. I then permanently killed the NPC.

The only possible problem is that this may screw up you supply lines. I have a couple "phantom" supply lines (they show up on map but there is no one assigned to them). I'm not sure if this is due to the few reassignments that I've made or not (I've killed reassigned provisioners but the routes don't go away). But, creating a settlement of invincible inhabitants would be an interesting experiment.