Re: If the author wanted a "killing is always wrong" shpiel, he picked the wrong villains.
Not doing everything to prevent someone being killed does not make one responsible for that person's death. Batman may be able to prevent prevent someone dying from AIDS by going to highschools teaching about proper condom use. Batman may be able to prevent someone from committing suicide by being their friend. Batman may be able to stop the deaths of smokers by buying and closing down all tobacco companies. Similarly, Batman may be able to save a lot of people by killing the Joker. But if he doesn't, he shouldn't be held responsible for the deaths of Joker's victims.