I don't know anything about the morality of the pre-revolutionary French nuns. But the French nuns we've heard about today, having misused their crucifixes in a very ungodly way, would be good candidates for those guillotines.
Those nuns were very holy and actually believed in the tenets of the Christian faith. The French Revolution was designed to wipe out the monarchy (Divine Right of Kings) as well as the Catholic Church in France. Why? Because they believed in God and tried to abide by His teachings. The Committee actually went so far as to decree that the week was to be 8 days long in direct opposition to God’s design of 7 days at Creation, and they renamed all the months, as well as re-numbered all the years. They were obsessed with rebelling against God. The nuns willingly went to the guillotine as a witness to Christ and as a sacrifice “to stem the tide” and the Revolution ceased 10 days later with the death of Robespierre.