It's an argument for murder, that isn't protecting innocents, it's killing them! And none of you, unless it's someone with the ability to see all variations of the future, can even be certain that this werewolf or any other would kill. Just because it's happened in your world does not mean it will happen here with all the precautions we take, precautions that are FAR more extensive than the ones people in this world took in the past and, I'm sure it's shocking to you, it worked for them even then.