I think he's saying "scariest in the long run," because the worst sort are (of course) much worse in the short run, but are less likely to last very long.
I sincerely doubt the sum total of human misery caused by the government in Singapore will ever exceed that caused by that of the North Korean government.
The point he's making is that a dystopia that achieves buy-in from a large portion of the population because it delivers wealth, cleanliness, and low crime, is much more likely to persist for a LONG time than a dystopia like North Korea.
You could have an authoritarian government that routinely tortures and executes political opposition and severely punishes minor crimes that ends up with the support of the majority of the populace because they like clean streets and a strong economy. That sort of government would be extremely difficult to uproot.