Sotomayor's argument, as I understand it, is that transformation into a direct replacement of the original work in a given commercial context is not fair use.

Sotomayor's argument, as I understand it, is that transformation into a direct replacement of the original work in a given commercial context is not fair use. So it's not fair use to transform a photo of Prince for the purpose of illustrating magazine articles about Prince, where the original, untransformed photo could have illustrated the article equally well. But presumably it would be fair use to transform a photo of Prince for the purpose of illustrating magazine articles about the history of pop art, where using the original photo would be inappropriate.