Many thanks
@Sighman and
@Jack Winter. I'd been ignoring the stealth/assassination/mats side of Ody since I bought it last year (seemed fiddly/unrewarding, was going to get around to it eventually), but manipulating a system into a dedicated setup where murdering the inhabitants is actually beneficial to them (sort of) is a masterstroke. It made me want to give it a go, in the same way that I'd definitely want to try a slice of Ameglian Major Cow.
So today I've have wiped out my first four settlements. The first three runs were pretty clean, but the last one took
ages - alarms going off, lots of guards with shields up, I needed several trips back to the Scorpion to recover/restock. Lots of fun, particularly a superlongrange duel with a sniper amongst some rocks.
I thought I'd finally eliminated everyone and relaxed into some systematic looting, then noticed that the doors to the bar building were open and there was movement inside. Turned out that the last four technicians and pilots were in there guarding the door. It's probably just coincidence, but kudos to FDev if survivors can decide to head to the Winchester, have a nice cold pint, and wait for things to blow over.