I belive that your recollection is correct. That didn't matter when George H.W. Bush subsequently took the same tack. He, unlike Gore, was excoriated for mentioning it.
Willy Horton was quite guilty as well. He commited murder while on furlow from prison. He was used in a campaign ad and the liberals said that it was race baiting because he was black. Never mind that fact he was a murderer. That to them was not the point.
On the acorn website, they poffer this defense: "We are their Willy Horton for 2009." Maybe they should look up Willy Horton before they equate themselves. Regardless of how Willy Horton was allegedly used, or portrayed, he was still a very bad guy. I personally think that thier analogy is appropriate in this regard at least; Acorn is a really bad bunch of nuts.