The analogy is deeply flawed because it fails to account for the future. Life does not occur as a single frame and so we have to be aware of probable consequences going forward. To extend the analogy, let's imagine the woman leaves the train unmolested. Somewhere in her psyche the lesson is clear: people can be attacked without any meaningful consequences being imposed upon her. So, she repeats her attacks, and more people are subject to them.

Conversely, extending the analogy in a different direction, after being beaten by her former victim, somewhere in her psyche the message is clear: if you assault someone they may well return the favor. Henceforth her desire to attack others is significantly reduced.

Simple stories are amusing, but there are no simple rules that are applicable to all situations. Life is relative, and - crucially - life exists across the arrow of time, not in a single freeze-frame. It is essential to understand these two basic facts.