Certainly the tetraphobia makes for a more appealing headline, and it isn't the first product to follow that pattern.
There was some suggestion, and even a comment from the company about some sports player that many were seemingly a fan of, but that sounds like a poor attempt to deflect away from the idea of "bad luck", which is certainly thought about very differently in our cultures.
Though I can't speak for anyone else, in the UK at least there is a deep-seated obsession from some with traditional bad-luck associations, including the number 13 (particularly Friday the 13th), walking under a ladder, breaking a mirror etc.
So while that particular example may be easily dismissed by some, it isn't by any means a belief unique to china.