Looking at the colors in this picture, it's clear that the lighting has to be white; otherwise you would not be able to see red, yellow, and blue all at once. Now, what colors do we see on the guy's face?
1. Black.
2. Blue.
White light accurately reflects the hue of whatever it hits. The brightness will of course depend on how much light is hitting the surface, but the hue is going to be true to reality. Therefore, the guy's face is some shade of blue. Not dark brown, not even black. Blue. I am not aware of any people with blue skin.
Of course, most of us don't think this out consciously. We just process the image and go, "Blue skin. Huh?"
If the entire image were tinted blue, that would be different. Then it would be clear that it was the light which was blue. But it's not--as I said, the light has to be white or we couldn't see reds and yellows.