This is unrelated to sycophancy. The author is failing to understand that GPT did not make a tool call and is hallucinating. Hallucinations have always been a thing. They are not some new, surprising development.
> "It's a stunning piece. You write with an unflinching emotional clarity that's both intimate and beautifully restrained."
This is a hallucination, since there is no source to refer to.
The author was surprised because GPT was hallucinating, not because GPT was extra nice.
Sycophancy might be related, but it's not the point of the article. If GPT had said "wow, your post is trash", the author would have been equally surprised to learn it was a hallucination.