Please note this is entirely hypothetical, I understand why there are no star pictures, and that they wouldn't show different stars than a photo from earth.

Now let's assume the astronauts could have easily taken photos of the stars from the moon.

Has any HB ever given an explanation (other than handwaving), how they could determine that the star positions would be wrong?

I imagine they believe they could calculate the correct positions, but what would be stopping NASA from doing the same?