I have actually referenced Duchamp's Fountain before in similar conversations about AI art because I think it's a great example of what makes art art. The art itself isn't the toilet, it's the act of elevating a toilet to the status of art. If you don't know the context of the physical item, it loses all artistic merit because the item itself is not the art. The whole thing is more performance art than sculpture.
I'll freely admit that LLMs can be used in art in a similar way. You can certainly make LLM output the core of some performance art piece, but that doesn't make the LLM's output art itself or make it interesting on any level outside the context of its creation. Engaging with that short story as its own art would be like primarily judging the Fountain on the aesthetic qualities of the curves of the porcelain.
Even if we consider Duchamp's creation an outlier - one may say if it were created, say by some random plumber, instead of Duchamp, this urinal would not be as important of art piece as it would be if made by Duchamp, there is a plenty of other artistic niches - say DJ or an interior designer, where the author does not create a thing by themselves, just combine existing items, yet we judge the art piece purely by aesthetic merit, irrespective of the who exactly was the author.
I mean it is as simple as saying - here is my statement, it was generated by an LLM, but I had prompted and edited it, or even simply chose a single generation out of 500 and this conveys my feelings and therefore is art.