You can already turn off "Co-Authored-By" via Claude Code config. This is what their docs show:

~/.claude/settings.json

    {
      "attribution": {
        "commit": "",
        "pr": ""
    },

The rest of the prompt is pretty clear that it's talking about internal use.

Claude Code users aren't the ones worried about leaking "internal model codenames" nor "unreleased model opus-4-8" nor Slack channel names. Though, nobody would want that crap in their generated docs/code anyways.

Seems like a nothingburger, and everyone seems to be fantasizing about "undercover mode" rather than engaging with the details.