Live, in media land, means real. It means what the audience member sees and hears in concerts is what is happening right there and then--not what happened in the studio six months ago. For a concertgoer, it means that the interaction between the person on the stage and the audience is genuine, not contrived, not premeditated.
Backing vocals are the antithesis of what a "live concert" is supposed to be about. As a consumer, I already paid upward of $10 for the album or cassette that made me think the performer was worth going to see live. If Headlee thinks I am not being hoodwinked by having to pay upwards of $25 to hear that exact same music at a so-called "live concert," he is only demonstrating his own lack of integrity.