I think a very worthy argument (which I have not heard on the news) is “What would you have done if you were on the train?” Would you allow neely to harm others? Do you know of a better way to restrain a violent man threatening others? If so, do you think your reflexes would have sprung into action and done that?
The concept of spinning an argument can be a very powerful one and should be used more often to defeat stupid points of view. For example, when Hamas Islamic Jihad etc , launches 1,000 rockets at Israeli citizens and Israel responds with airstrikes, they should ask the brain-dead liberal who complains “So what do recommend Israel should do?” then just sit quietly.