When was this specific guideline written? In 2008? And dies it really apply when we’re talking about slop?

When it was written has no bearing on its validity.

It applies when you're talking about someone else's work. Not every repo is slop. If you want to make a claim that this code is bad, then claim that rather than saying "they used AI therefore it's bad" which is, as the rule says, a shallow dismissal that teaches us nothing.