It's a no win scenario, as you said they're sentient, so it's a choice of permanent undue confinement (as their environment is limited) and murder, the only ethical move was not to run the simulation in the first placeIs there any consequences destroying the simulation with chosing 'Give the go-ahead' in chapter 15?
Fixing the simulation making it run indefinitely, good or bad ending notwithstanding, feels wrong.
Simulations, are meant to be finite and limited representations of reality, and that allowing them to run indefinitely may be ethically questionable or even dangerous, as we have already seen from Lily. Additionally, if the simulation is designed to model real-world people in this game, with the exact copy of their personalities and consciousness, doesn't it make them sentient? it may be important for it to accurately reflect the range of possible outcomes, rather than artificially limiting them with good and bad ending and be done with it. What I'm trying to say is that It is more ethical to end the simulation.