As it should be for traitors. I'll bet there wasn't another coup attempt for a very long time.
Cruelty can be a powerful deterrent. Crassus decision to crucify the prisoners taken in the Third Servile War along the Appian Way ensured there was no Fourth Servile War.
The BBC had an episode about the Queen Elizabeth I (1558) and how she handled an aborted coup. She gave the torturer/executioner a chilling order, "Think of something new."
Knowing how brutal those times were, one can only imagine. The episode didn't go into much detail, IIRC, only showing the executioner telling the victim, as he probed his crotch, 'You came into this life through here and will leave it the same way."