He's obviously a bear of somewhat restricted brain...
To change policy would be like a tacit admission of being wrong, so making the glorious leader a little less glorious.
Look how long it took Catholics to officially accept the Copernican (and earlier than Copernicus, though he takes the credit mainly) Heliocentric model if you want and example of how long some people want to give the appearance of maybe not admitting they got something wrong.
Also the expectedly rapid (over a decade or less maybe) industrialisation of NK if the floodgates were opened would tear the country to bits as people would need internet to do business and then folks get exposed to ideas like hotdogs, cocaine and recreational gun use. Then before you know it they're all spelling colour incorrectly and the government is at sixes and sevens.
Then again, sounds like a CIA wet dream.