This is some really fascinating video. And what Rod says of race is very true.
Serling, like Gene Roddenberry, and Kurt Vonnegut leaned a little to the left in their politics, but as honorably serving veterans of WWII, I don't begrudge any of them whatever worldview they felt necessary to embrace to make sense of what they'd been through.
IMHO Serling was tremendously insightful not only in the observations he made of human behavior, but in his ability to spin them into didactic fables and allegories.