The poster probably means that NK is NK, because of its own extremist ideology. So the only way to really get rid of extremists seems to be to become more extreme than them.
I didn't say it was the only way of getting rid of extremism. I'd even argue that getting rid of extremism by installing a extremist regime makes as much sense as chopping a leg off because you want to get rid of a headache.
It is important to remember, that no nation no matter how great its tales of freedom or historic shame might be is immune against extremism.