Yes, I agree that Mick Jagger would succeed where Joshua Bell failed, but not simply because more people know who he is and/or because more people like his music. It's also, I think, because Mick Jagger represents a kind of music that encourages active rather than passive engagement. That is virtually what distinguishes "entertainment" from "art," and that is what I take to be the point of the Washington Post's experiment. Suppose Mick Jagger had played at rush hour and gotten no response. I don't think rock musicians would take this as a sign that rock music no longer has any bearing on the lives of the average Joe, or that the average Joe is now incapable of appreciating great rock music because of the nefarious influence of Corporate America. I think rock musicians would concede that maybe rush hour isn't the best place to test the aesthetic sophistication of audiences, and would probably consider different ways of entering listeners' lives.
Weingarten, like most defenders of Great Art, seems less willing to make concessions or to place the onus on makers as much as listeners. He wanted a pretext for lamenting the dumbing down of culture in a way that places the blame on consumers rather than makers. The experiment was to take a type of music that appeals to passive contemplation and the recognition of the inherent value of abstract musical structures, and to place this music in a situation where passers-by can be counted on to be preoccupied with more pressing matters. That is why I don't think the Mick Jagger analogy works. The experiment was designed to produce a diagnosis of the way classical music's values are promoted and received, which has little bearing on the way values are construed in other musics.
So yes, I was claiming that the experiment was asking commuters to choose between Great Art and arrive to work on time, but I also claim that this proved nothing about the tragic neglect of Great Art--except perhaps to show how disingenuous it is to blame that neglect solely on consumers and not makers.