The problem is the "scorpion" depicted in the petroglyph does not have that "unmistakable sting in the tail". It's more of a lobster shape -- all rounded. If anything, it looks more like a depiction of just another desert scorpion than a depiction of the constellation with its characteristic shape.
And then there's the problem with the fact that the petroglyph depicts TWO large scorpions and maybe one or more smaller ones depending on if you interpret the eight-pointed "star" as a star or as another smaller multi-legged scorpion.
