The real question is, what happens when the AI starts producing text outputs that are indistinguishable from a real person's post? That's already possible. If the person knows some basic English he can read the AI response and re-write the same thing using his own words but there will also be other, better "humanizer" tools out there. (they are already available as far as I know).
My previous take on that was if they're going through enough effort to have to re-write the AI post, taking almost as much time as it would to just write a post (or maybe more), just to avoid the detectors then I guess thats OK. But the recent output of AI shitposts has taken a turn for the bizarre... and they're not any easier to read. artificial shitposting is the new thing.
If the user rewrites the AI text, the text ceases to be from AI, becoming a text from the user himself.
The problem is with those who copy-paste.
But gradually AI systems will produce texts that are more difficult to detect, and it all depends on the requests made by the person.
Unfortunately, it will be difficult to understand if a user is writing with AI or not, in a single post.
It will be necessary to analyze more than one post. We will have more work, but only this way.