The kind of rhetoric that you should be able to say anything you want consequence-free flies well in the US. Not so well anywhere else. If you praise the Nazis in most of Europe you get in trouble, especially in Germany. I don't quite see how it would be different in South Korea.
People should be able to declare some speech as dangerous speech, because it does way more harm for society than good. The usual problem is that sometimes people try to do this with speech that is not dangerous. Dangerous is very subjective and there should be no such thing as the Ministry of Dangerous Speech.; but if 99% of people agree to something, well, it is a bit less likely that the "dangerous speech" is just an autocracy of the masses. If you disagree so profoundly with 99% of the people around you, then maybe there's some other society more fit for your views.
I wouldn't call NK Nazis. They have a horrible government, sure, but equating them with what the nazis did throughout Europe is straight up insane. I don't see NK brandishing their own version of Lebensraum, or trying to invade every country on earth. They're a dictatorship sure. But not the nazis.
And besides that, what does it even help us with to ban words and shit. At this point anyone should've realised that this is just a farce to whitewash our past without doing anything about fixing our problems. There are plenty of people walking around saying straight up nazi shit, but hey, at least they don't brandish the forbidden symbols and don't say the three illegal phrases. So they can't be nazis. I mean, look at Germany, they did such a good job at denazifying that they banned the symbols and the phrases but conveniently forgot to criminally charge the sixty thousand officers that were directly involved with the shooting and execution of jews during pogroms. There's a reason the "Persilschein" exists.
Pro tip: If you're in a country at war you should avoid publishing remarks about how things would be better if your country lost and was ruled by the enemy.
I mean, if you really believe in it go ahead and use your voice, but be aware there are likely to be consequences.