I would refuse to even engage with the piece on this level, since it lends credibility to the idea that the creative process is even remotely related to or analogous to gradient descent.
The author set up an interesting analogy but failed to explore where it breaks down or how all the relationships work in the model.
My inference about the author's meaning was such: In a sharp peak, searching for useful moves is harder because you have fewer acceptable options as you approach the peak.
But that's not what the author's analogy would imply.
Still, I think you're saying the author is deducing the creative process as a kind of gradient descent, whereas my reading was the author was trying to abductively explore an analogy.
It's somewhat like saying cars are faster than motorbikes because they have more wheels-- it's like with horses and humans, horses have four legs and because of that are faster than humans with two legs. It's wrong on both sides of the analogy.