They were wrong in the sense that no widespread violence against whites ensued in the Reconstruction period, maybe because the freedmen realized they were vastly deficient in weapons. Of course the scholars who deal with the Reconstruction period are only interested in white violence against the freedmen, but it doesn't appear that there was much black vs. white violence then.
Unfortunately the era of slavery left many blacks with a lack of respect for the system of justice and law enforcement which has persisted until the present. Every year more whites are killed by black criminals than blacks were killed by lynchings in all of American history.