A racist is less likely to have black friends than a non-racist. I'd suggest that a racist is even less likely to have black co-founders than a non-racist.
edited to add: The reason the "look at my black friends" argument is mocked is that in many cases the friends referred to are not friends in the true sense of the word. There's no such distinction possible when talking about a co-founder. One either is or is not a co-founder.
This is a dangerous oversimplification of what "racist" (or any negative bias) means. There are many people who have no problem associating with individuals of [insert class here], but would be less likely to hire them, etc. Racism, like everything else, is a spectrum, and it's critical not to characterize it by its most extreme elements.
How can I simplify the meaning of something I haven't attempted to define? How can I mischaracterise the nature of something I haven't attempted characterize?
One can overlook one's own prejudice with regards to a few friends from categories which their disregard, having gotten to know them as /people/, and still regard strangers in those categories with disdain.
