Until Turner’s rebellion, Virginia had been moving towards emancipation. (Britain freed all her slaves in 1833). After that, the movement went the other way, for fear of the slaves.
Turner effective smothered the anti-slavery movement in Virginia; had that movement succeeded, a civil war would likely have been avoided (it’s difficult to imagine a Confederacy without Virginia).
There was also the experience with emancipation in the British Caribbean. There, the newly freed slaves disdained work on the plantation, and work in general. Production collapsed. It was thought the same would happen in the U.S. It was thought it take generations for people who associated work with being a slave to be turned into reliable free laborers.