Basically, this is the story I got from Weber.
In 2000 there was a "thing" called Simpson's Fanfest? I think. To honour that Weber made the Simpson's grills, as a Sears exclusive. Given that, I'm guessing Weber was approached by Sears to make the grills. I'm not sure how well sales went, because after some time, Weber took the unsold grills back and sold them off.