I'd like to see how you analyzed the race of github contributors. I'd also like to know what "plenty" means. Personally, I strongly suspect that you'll see fairly small set of race/location/income combinations.Why, me and my friends and colleagues, Chinese and South African and Ghanian and Kenyan are on github. I'm very offended you suggested only white people can afford to be on github.
Given that we're not really talking about color, per se, I seriously hope that you don't honestly believe that statement.
You specifically mentioned "white males".
It takes half a day to write something you can put on github. If anyone can't do that it's because they're not as experienced as those who can. It's not much more effort than writing a resume. The point of github is so people who aren't interested in brain teasers can demonstrate their ability to write good code.
You can argue people who aren't good at programming enough to be able to write something in half a day should be hired anyway, and I'll tell you the communism experiment is over.
You, sir, are racially biased.