That's a dangerous line of reasoning. Depending on who you ask, people won't consider a lot of things "equal or better".
In no particulary order, a lot of people would not apply ethics to: Animals in general, pets, children, woman or all people of different ethnicitiy, religion or even political views.
I'd argue that ethics should be applied to all living things. Well, at least all things capable of suffering, but that keeps people arguing again - doctors even used to think that human babies aren't fully capable of that.
Regarding the original question: The simulation isn't alive. Stopping it won't 'kill' it, assuming it can be resumed. Deleting it, however, argubly is be unethical, yet it does not cause suffering at the very least.
I'm vegan. Even if you argue that plants can suffer - it's the least amount of suffering I can cause without starving myself.
Also "applying ethics" does not mean it's automatically unethical - just that I think about it beforehand instead of categorically thinking "it's okay because I'm something better".