Why, it doesn't make any sense

This girl said she is playing '玩“爸爸和妈妈睡觉”的游戏' with her brother. She sounds very familar to in adult sex life already. She can make up anything with instruction.  Mr. Zhang didn't even mention the name of game. He just said the boy is on the top of girl when he saw them before he took them out. If he has dirty mind, he could guess the name of game.

I feel Mr. Zhang is innocent due to the girl's express and their parents' reaction on the internet. They sounds very farmilar with law why not sue Mr. Zhang again of internet abuse again??! It's about money due to the girl's sex knowledge. She probably saw her parents and she knew what man's part looks like already. Her parents should be punished instead!!