Appropriation art and sf book covers

How a Science Fiction Book Cover Became a $5.7 Million Painting: Appropriation art that relies on expanding size, not shrinking compared to the original, for the claim of transformativeness.  E.g., from a program: “[The paintings] are unusual for Brown in that they are based upon paintings made specifically to be reproduced and reduced in scale – their originals versions were commissioned to illustrate the covers of popular science fiction novels. By enlarging them so dramatically, Brown merges the conventions of science fiction illustration with the spectacle of large-scale history or landscape painting by artists such as Jacques-Louis David and J.M.W. Turner.”  It’s not clear how much of the artist’s way of speaking about his work, and his gallery’s, have been affected by fair use case law—and, especially for an appropriation artist, why shouldn’t case law have influence on an artist’s self-concept, as the rest of culture surely does?  Also, this news comes not from the US, but from a country with a distinct fair dealing regime, and yet here the artist is—how should we think about that?