It's possible they are safeguarding for possible future changes of copyright law that would give Microsoft copyright over all Copilot contributions. This may sound paranoid but, as far as I know, exactly who counts as an "AI operator", how much authorship an "AI operator" has, and who gets copyright, or whether AI contributions are even in the public domain, are legally untested and unclear issues.
The US Copyright Office has said that AI output from human prompting is not copyrightable. There are caveats, but iterating on prompts results in output that's nobody's IP.
Because it's nobody's IP, Microsoft is already in a position where they could just use, remix and/or distribute that output however they want to today.
tough luck for MS or other "AI" providers claiming any ownership, since if they can claim ownership, then it opens up the discussion of what license the AI output really is under, since it was trained on GPL licensed data.