I would say you are spot on. Wow, you're reading some pretty high level English here. This question is complicated because you're dealing with an almost philosophical statement. Very po-mo, as well.
Just for some clarification, in case you're not familiar with it (or perhaps other readers), to "reify" something is to take an abstract concept and make it real, or concrete. It seems to me that your question hinges on the meaning of that.
I'm also going to say that this passage seems like it was written by someone in the art field. Often they use philosophical terms in more loosey-goosey, or at least less strict, ways than a philosopher would use them.
So in this passage, to judge from the context, I would say that the writer is arguing that while Andy Warhol played up his independence from society, made himself out to be the "alienated artist type" (the phrase "who mimics commodity relations" is clearly an arty reference to casual, post-modern, quasi-Marxist thought, e.g., that which may be seen in Herbert Marcuse's One Dimensional Man, Guy Debord's Society of the Spectacle, or Jean Baudrillard's Simulacra and Simulation) who hates to prostitute himself for the popular culture, wanting to poke fun at it and profit from it at the same time, Jeff Koons has lavished himself in the very same culture and enjoyed playing up the pop diva aspect of being an artist. In this context, the writer is saying exactly what you suggest: Jeff Koons has created an "authentic art creation" out of himself.
This is, in fact, a very post-modern sort of thing to say or do. I have heard people say Kanye West tries to do this, though I personally have my doubts.