Balanced against the science fiction that Koreans could be programmed into welcoming an invader with open arms is the real life fact that somebody was put in jail for the crime of writing poetry.
Since you don’t seem to be aware, propaganda could have negative real world impact influencing (not even mind control!) a small group of people. Imagine the impact is only a group of 5 people “defect” to North Korea under the belief it is some paradise. Thats harms.
That's just bad advice. How can you ban bad advice? I can't imagine what society would be like if nonprofessionals had liability for the harms that came to other people as a result of acting on their opinions, the way we have liabilities for doctors or lawyers in a client-provider relationship. Yeesh, you'd be putting people in jail for the crime of being dumb online.