He was not stuck. He could reuse the bundle id after changing the Personal Team's Bundle ID to another one.
Come to think of it, if a Bundle ID used in personal teams can never be used again, it can be maliciously used to lock many potential Bundled IDs.
Also, there are good reasons to want to keep a bundle ID. For example, you may have created a lot of third-party accounts, setups, and integrations like Firebase with the Bundle ID.