(see the cite to campbell v. acuff rose, etc)

In fact, the precise argument y'all seem to make is disassembled in that case, because it's what the original court of appeals decision was in that case :

"The Court of Appeals reversed and remanded, holding that the commercial nature of the parody rendered it presumptively unfair under the first of four factors relevant under § 107; that, by taking the "heart" of the original and making it the "heart" of a new work, 2 Live Crew had, qualitatively, taken too much under the third § 107 factor; and that market harm for purposes of the fourth § 107 factor had been established by a presumption attaching to commercial uses."

They also explicitly said: " The statutory examples of permissible uses provide only general guidance. The four statutory factors are to be explored and weighed together in light of copyright's purpose of promoting science and the arts. Pp. 574-578."