Blue eyes are acknowledged to be more sensitive to light, and that's an advantage in areas with less light more of the year, such as northern Europe—where there happen to live most of the blue-eyed people on earth. So, how can it be neither positive nor negative? Perhaps a European advantage for surviving in Europe is just too politically incorrect a thought to harbor in one's mind.
The whole thing sounds like B.S. anyway.
My father has green/brown hazel eyes. My husband has green eyes. One of my children has dark gray eyes (not blue, not green, not brown) and the other child has greenish/light brown eyes. Very strange combos.
I have pondered that myself. My vision is exceptional in conditions that other claim are "pitch black" (I will spare you the stories). The only problem with that is that I am painfully and literally almost entirely snow blinded after short exposure to sunny winter conditions.
As much as I like and want to support the theory, we would have been forced to have been nocturnal creatures capable of completing life sustaining tasks as well as our diurnal relatives or have invented slit goggles at about the same time as the mutation.