Well he is against free trade, which is an open market. He is forcing electric companies to keep unprofitable coal plans open. He is attacking companies on social media. Do you watch?
Coal is for national defense. It's NK's main export. He's not bombing them with bombs, he bombs them with low coal prices. It's easier than enforcing sanctions and we get electricity.
Once the price of coal goes down due to a flood of new supply the power plants are suddenly viable again AND North Korea's biggest cash cow dies. Pretty brilliant if you ask me.
Economically unviable yes, because the price of coal was too high due to low supply. That's DC fascists "regulating" the market. So rolling back those regs is a double whammy.