You aren’t a jerk but, hopefully, jerked some sense into others. How someone’s deliberate act can cause others to live in pain - the same thing he wanted to escape from.
Although you are correct, I think that misses the point.
People who choose to off themselves are usually so consumed with emotional pain they are unable to understand that the method of their suicide will possibly bring distress to others. This guy probably just saw the train as a huge, deadly force that could end it all quickly and did not consider that a human being was driving that train.
Also, people in such a state usually have such low self worth they are convinced that no one will care if they kill themselves. Indeed, they are certain everyone else will be better off without them. They actually think they are doing everyone else a favor by killing themselves.