It's a very interesting find indeed, but I find this remark very silly. It doesn't take a rocket scientist to look up at the sky and notice that there is a sun, a moon, and the stars, or to depict them as stylized images.
This doesn't disprove that the Bronze Age tribes in Germany did astronomy, in the sense of mathematical calculations, but it doesn't prove it, either.
Presumably, some degree of astronomical calculation is necessary for any society that needs to know when to plant crops. But the Sumerian astronomers were well beyond anything that can be proven from this object.