As I see it, those choices to “murder or not” are trivializing murder, but it can be OK to trivialize crimes/immoral actions in fiction.
The question is: when is it OK to trivialize crimes/immoral actions? That’s a complex question, but there are some reasonable questions you can ask yourself:
- Will trivializing the action influence people into thinking it’s OK? (Do a lot of people already think it’s OK?)
- Do you have good reason to think trivializing the action will be especially hurtful to real-life victims of similar actions?
- Are the victims especially vulnerable?
These are the same kinds of criteria we’d use to discuss jokes which we tell specifically to trivialize. This is part of why race jokes and rape jokes can be especially bad.
Reasonable people can disagree about individual cases, and that’s part of why I think in a democratic society we have to make it legal to tell pretty much whatever jokes you want, write whatever stories you want.
But I think we can all agree that there are legal jokes that are unethical to tell; similarly, trivializing choices can be unethical. (And we’re certainly not going to publish any material that we believe to be unethical to publish.)