Nice article, Roswell. I think you're dead-on right, unfortunately.
Avant garde does denote innovation. It should suggest, in the case of jazz, a musician or composer who is out in front of the front, ahead of the times, one who's trying to find the next stage of the music's evolution. When writers or critics use the term they can mean all of that, or something less positive. More crucial is what most readers understand from the term. Intention is one thing, but reception is another; I think most readers understand avant garde to mean, simply, "you're gonna hear some weird-ass shit, possibly something you won't recognize as jazz, or even music." Now, that doesn't bring people in large numbers.