Except that's not how the chaos system actually works or plays out. Chaos is supposed to be roughly summed up as more bodies=more plague and filth and crimes and unrest. The non-lethal option for the first target results in him being a weeper, more plague but it leads to no added chaos or rat spawns.
It's best not to think about it because the story is fairly cartoonish and the world is ok enough to be immersive but from a gameplay perspective this makes no sense. I should preface that nothing in these games is difficult regardless of difficulty because you're always playing with debug commands but if you want the "more difficult" route you need to play the "easier" way by killing everyone and failing stealth on purpose. There's no added guard presence or rat spawns or less loot etc. for players going mostly or completely non-lethal who would be the players seeking more challenge.
The difficulty scaling curve is reversed and confused. This works to show the narrative consequences of your actions and choices but again, the story is very childish, good guys, bad guys and a betrayal twist. So seeing more death and despair doesn't matter to me especially on repeat playthroughs. The game design has mixed up priorities and a lack of focus.