I think your excellent poll is unnecessary. It's not about policing the creators (that doesn't seem, to me, to be what OTW or AO3, or Fanlore etc, is about at all) but asking the user uploading a work to decide this: is your work fannish or is it original? If you consider it to be original and in no way fannish, if you can't attach a fandom tag to it, then it's not for AO3.

The key thing is in your post: some of them are openly hostile to fanwriting. Do not want. And while I don't believe that people who hold that view are likely to come near AO3, I do want to discourage users who value original work ( and by original I mean not borderline, but this is orginal and not fannish at all, says the author) over fan work.

If the user thinks of their historical novel as belonging in a fandom tradition, then come on down. Etc.