Robespierre the Incorruptible, Robespierre the Daemonic (2014)

I had an ancestor who was a lawyer and a competitor to Robespierre before the revolution. Apparently he just escaped the death penalty with the death of Robespierre.

His position on the death penalty -- at least according to himself -- never changed. He came to the belief that the only way a republic would survive, was if it was a republic of virtue, and that it could only contain virtuous people. People who were not deemed virtuous were to be executed. Once all the non-virtuous people were executed, a republic of virtue could be established, and the need for the death penalty was no longer needed.

As he himself would argue about the necessity for the Reign of Terror, "virtue, without which terror is baneful; terror, without which virtue is powerless" -- effectively, to prevent the usage of the death penalty, we must use it aggressively, so there will be no need to use it later.

Please explain. In what way? Both men, both leaders at the top of revolutionary regimes. What else?