I could not tell from the article whether the use of LLMs was allowed in the peer review. My guess would that it was not since this is unpublished research.

In general, what bothers me the most is the lack of transparency from researchers that use LLMs. Like, give me the text and explicitly mention that you used LLM for it. Even better, if one links the prompt history.

The lack of transparency causes greater damage than the using LLM for generating text. Otherwise, we will keep chasing the perfect AI detector which to me seems to be pointless.