I'm a big advocate of the Bad Guy Off Button because it is demoralizing and unfair to turn a player's character into a killer against their will.It really doesn't. All that is required in the current rules is that the player says that they do wish to do nonlethal damage.
Which frankly is bizarre and I don't like it. Because if that's how it would work, then every time you kill somebody with a melee attack, it is pretty damn immoral, as you could have just as easily not killed them. Of course in reality that's not how it would work. If you have some proper weapon, it is very difficult to knock someone out safely, so using lethal force could still be justified.