My take is that all white people in the US have been unintentionally racist at some time in our lives, in some way or another. One reason is that the national conversation about race is so low-level. Kids from kindergarten through Socially Awesome high school get African American history almost entirely through the designated month, or with black people as objects of other people's actions (slaves to be freed via war, protesters who got firehoses turned on them, little kids jeered for going to school) rather than people who achieved things, said things, wrote things. Similarly, I teach first-year writing in college and I get people who think all Native Americans are extinct, Pocahontas, or football mascots. My high school never covered the internment of Japanese-Americans during WWII. And so many white people have no idea why various ethnic groups have the customs, stereotypes, etc. that currently exist. (My black students are less ignorant about Natives because there's a decent amount of mixture there, sorry Cheroki-Chan, but one kid who did a research presentation, in describing a Chinese restaurant, actually used a shoop of a dog in a fry basket. Fail! Literally, with extreme prejudice!)
Also, we are beneficiaries of a society that is set up to revolve around the interests, tastes, needs, and economic promotion of white people. (Specifically men. One thing we can agree President Obama is not? Female. Unless your conspiracy rabbit hole goes very deep indeed.) Accepting this without question is kind of jerky, but that's certainly what I did all through, say, my bachelor's degree -- aversive racism is the kind where no crosses are burned, you just can't imagine hanging out with a person of X or Y race. I had no black friends-friends (one work friend) and one Asian housemate, and that was it, and I didn't notice even as my white friends and I went to campus to see the Ice-T/Public Enemy concert, which we thought we were being totally edgy, street, etc. in attending. It took having to take a certain number of literature courses for my major, and picking one about the African American novel, to open my brain even a tiny bit -- but I didn't have black people who were outside-of-work friends, or date anyone black, until after college. Moving to DC for my first real job was immensely helpful in that regard.
So it's not the Avenue Q sense of "Everybody's Racist" (which is a song used by a lot of white folk I know to accept and excuse their own dumb jokes or assumptions), but yeah, Borb did probably harbor some racist attitudes -- not because they were in Virginia per se, but because they were in the US. Black people in fandom still get shit for cosplaying characters that are not black in canon, for example. The Wire was an extremely well-written TV show, but at the end of the day it's still about black criminality, not black scientists or whatever.
Tl;dr That's why I think Chris got his unthinking racism from Borb, AND TV, and and and and and. You see a lot of black kids in those elementary-school pizza party photos? Anywhere in his high-school life except the basketball team? Yeah, me either. As the Palmolive commercials used to say: You're soaking in it.