I wouldn't be surprised if the AI-companies end up earning from both sides: earn from creating spam, and earn again from detecting their own spam. It's like creating virusses to sell your virus scanner.
I think it's called monopoly or Cannibalization and that's exactly the point why this AI companies are busy creating new tools to still maintain it's position in the market. You're right! they are profiting from the both side.
To OP don't you think it makes zero sense to fight something with the same thing? you want to fight AI spam with AI detector.
The solution you offer is already stereotype or judged before you even posted it, as long as you already have an issue whatever you offer now as solution will be sense as a means to justify your actions.