I have to agree with him. It is not so much that we are a nation of racists, just that we are cowards when it comes to race. He described what he meant by saying; at the workplace, their is plenty of diversity, but when we go home, we tend to segregate ourselves.
I am a college student at UC Santa Cruz. What he described was UC Santa Cruz. Plenty of diversity. No signs of racism. However, after classes are done and it is the weekend, I find that different ethnic groups segregate themselves. Asians hang out with asian people, white people hang out with white people, etc etc. My experience tells me he is right.