In this one, a homeless black guy was harassing passengers (No mention that he was threatening death), and another passenger stepped up, took the knife he had in his pocket, and stabbed the homeless guy to death? And in this case, the one who did the killing left the scene and also had a weapon on him - much worse than what Penney did - and also bludgeoned the homeless guy to death.
However, he had something going for him that Penney doesn’t - he is black. The grand jury did not charge him, and he was released.