My comment is definitely an oversimplification that takes into account the rest of the context of the article which outlines all the differences which makes the author's work transformative enough to count. You're right that derivative works aren't a straight up protected use as my comment stated. However, "Not at all" is wrong, because derivative works are protected within the doctrine of Fair Use provided the work satisfies enough of the four-rule doctrine to qualify [1]. Transformative works are a subset of derivative works which are protected [2].

EDIT:

[1] https://www.copyright.gov/fair-use/more-info.html [2] https://foundrylawgroup.com/copyright-copywrong-what-are-der...