I remember reading how the left neck came about by accident, they didn't have another replacement while touring, but Dusty liked the better saddle and pressure/sustain of the E and A. It sure looks weird, but my hunch is that to the ZZ Top devoted (and there are a few, also to Dusty Hill's playing which never did much for me) this bass will sell well. I think reliced new basses silly, but this looks well-done.
I wonder whether they also broke a wire with the pup as Dusty's original Tele had, giving it a distorted sound which he loved. On return from a luthier for another repair, the pup had been repaired too - much to Dusty's horror - altering the sound of the bass completely. He then had "broken" Tele single coils handwound for him.