Well, you are looking at it out of context. In this case I was just covering a game for another DM. And it's often hard to take over just about anything from another person.
That's true.
Generally, if I'm "guest DMing," I provide pregens (or let experienced players make their own new characters) for a limited run game, expected to go 1-2 sessions, or whatever. Certainly don't want to contaminate someone else's sandbox.
You seem to know these players' preferences so why not either adjust to them? Or be explicit that you absolutely will not and they really don't want you. Some tables are just not a fit.This group of players are the type I would normal not agree to run a game for as we are night and day. For example, y game is unrated and they would insist on a PG-13 game with nothing that would 'trigger' them. They would be fine with a mayor feeding innocent citizens to an owlbear to thin out the population a bit; but they would go crazy and run from the room if I mentioned some drow slavers with some gnomes in chains.
But if you're willing to answer, what table IS a fit for vindictive execution of PCs. I mean you KNEW your doppelgangers would slaughter the group, that was the primary intent. Where's the fun for the table?
Though I would not say that we could never game together. Just take one of my other groups. So they are all 20 somethings and were all excited to play the new Spelljammer 5E. Their DM did not want to run it though, so they put up and add. After a couple weeks of no takers, they came to me. I run a 2E spelljamming game for older gamers. They asked me to run the game, and I told them we can't game together. I'm an Old School Unfair Unbalanced Hard Fun type.....and they game 180 opposite of that. Then they offer to play the game my way. So of we go into the Black. The first couple of sessions were a bit rocky(and not just from the murderoids!), but they never complained once. And a couple more sessions and everything was going smoothly. Today, they play the Adventure is Survival, Combat is War, Hard Luck Nitty Gritty game with no problems.
They found that many things they thought were "so bad" about my game, were not so bad at all once they played things out in the game.
If the table is a fit for the style great.