You know, thinking about it a little, I'm pretty baffled by it, too. At the time I was too angry about the idea in general to wonder where it was coming from, but now that you point it out, I'm confused. It seems like a weird question to ask of this time period (especially when it's the only question asked, as this was), since beyond a few attempts to prove that light-skinned people did everything cool (as you point out), race in this time period is usually not a big issue. I have no idea what the underlying point was.