Violent games encourage violence

I boarded the bus to go to a meeting place with a friend. The inside of the bus (in Vancouver) was crowded as usual. In the crowd, I saw a five-year-old or a little older child who was holding a fake gun. He was pointing at the passengers, and he said, “I killed you.” Some were laughing, and some were looking in surprise. I was thinking, Should I say something to his parents, considering watching violent movies and pointing guns at people, that this is not a good thing to do, even as a joke, and what effects it could have in the future? (Violent games encourage violence.) But I didn’t have a chance at that busy time. Even if it was time, I was wondering how to start the conversation, that would not cause more trouble with parents. I just left the bus and started thinking, How can I act in this kind of situation?