Literacy is dead. You can call an action primitive and in a separate sentence sarcastically congratulate the culture.

You can have a non primitive culture that includes primitive punishment without having a primitive culture. Thats why the sentence makes sense.

If they thought it was a primitive culture the punishment would be fitting and specifically calling the action primitive would make no sense. If they thought it was primitive they would just say what you're accusing them of and refer to the culture as primitive shit.