Why would anyone encourage building such a tool, I can't fathom.
I've noticed that a lot of the supposed hallmarks of "AI slop writing" (em-dashes, certain multisyllabic words, frequent use of metaphor) are also just hallmarks of professional and academic writing. (It's true that some of them are clichés, of course.)
It seems like most efforts to instruct people on how to "fight back against AI writing" effectively instruct them to punish highly literate people as well.
I think it's often still possible to tell human writing that uses some of the same tropes or vocabulary apart from AI writing, but it's very vibes-based. I've yet to see specific guidance or characterizations of AI writing that won't also flag journalists, academics, and many random geeks.