At first, I thought she was banning him because the report of trying to sell a crystal they didn't believe he got, but she talks to the bishounen streamer afterwards mentioning he would be aware of the streaming. How is banning a newly famous, and powerful people useful for your organization?... a team of B ranks last chapter said they needed their special strategy to fight orcs, he effortlessly fought orcs, etc, you know hes strong if you're aware of the stream.