I think the accidental alert helps Trump in rallying voter support for his hardline stance against North Korea.
It emphasizes, in a few months if not already, that places like Guam and Hawaii are never more than 20 or 30 minutes away from complete nuclear annihilation if this can is kicked down the road any longer. That North Korea already had missile-ready sized nuclear weapons and missiles with the range to hit not only these pacific islands, but any city in the United States. All that is left for North Korea is to perfect their re-entry capability through the upper atmosphere, to threaten the United States. And threaten South Korea, Japan and other nations in the region.
And most importantly, to proliferate that nuclear missile technology (or the actual weapons) to any nation or rogue group that wants to buy them, from a North Korea desperate for cash, that can't even feed the soldiers of their military.