Moshe Rabbeinu's job was to try to make peace with Korach. He tried to correct Korach's mistakes and set him on the straight path. He tried to help Korach in every possible way. However, nothing succeeded. There was no choice but to punish him.
Some people deserve punishment.
However, that is not our job. It is G-d's job. He delivers the reward and punishment. G-d punished Korach and all of his followers. Mom, what you are saying is that I should not try to teach this boy a lesson.