I'd zap that photo back to the folks in Walnut Creek. They could tell you if they had a bad run, or if they want that one back so they can get some credit. Especially if they are new, recently received tires.
OTOH - if I had to run 'em, I probably would - it's hard to tell the depth of that split, and what it will do when everything is pumped up to pressure. If it's a deep split, it's above the bead, so it should not blow there. But, sidewalls have the least amount of thickness. My guess is that is the overlapped casing, and the sidewall didn't quite have enough material to completely cover it. The casing wraps up from underneath, over the bead, so I think you are looking at the end of the material.
hope that helps,
- Jim