I'm not sure where you're getting that from — it isn't mentioned on the about page[1].
I suspect you've made that assumption because they happen to be diverse, and the stereotype is that computing itself tends not to be. However, I think that is exaggerated, and projects such as this one aim to redress the balance.
But I don't think that's the primary aim at all — the primary aim is to exhibit photographs of people involved in open source, in an attempt to raise their profile.
> The project is comprised of portraits of notable and unsung heroes who dedicate themselves to the creation and advancement of our open source technologies.