You also have to realize that this is the English section of the forum, if you ran the same poll in the [insert any other language] subsection of the forum you would probably get very different results.
I have some real doubts about it. What's the biggest non-English subforum? German? Don't expect too many people that fall out of the core category (I'm German myself, btw).
One thing is true: bitcoin seems to have some success in China. Assuming most Chinese forum member don't post in the English subforum, you're right, they're skewing the results quite a bit.
Ok, I realized that is true after I posted it, if you went to the German/Polish/Russian subforums you would get mostly white. But if you went to the Chinese subforum my guess is most would be non-white. I am not sure about Spanish, do Argentinians consider themselves white?