It seems from the photos that the excellent Gordon low rack is not centered, and is actually to the rear of the axle. The ability to move weight around within the panier can make up for it's initial position. It does seem as though the more stable position would be behind the bolt, otherwise the bike itself would not be properly ballanced.
I also got rid of a front rack shimmy by getting rid of the perfect ballance with which I had initailly packed the paniers. What might really have been happening was an alteration in fore and aft loading, but either way ballance, within reason, is not all that big a deal.