That certainly may play a part in the reasoning but I doubt it's a more pressing concern than the death toll and economic destruction that South Korea would fac

That certainly may play a part in the reasoning but I doubt it's a more pressing concern than the death toll and economic destruction that South Korea would face if full on war broke out. Not to mention that even if N. Korea were to be "liberated", I'm not entirely sure the South would want to bear the cost of reunification. Korean reunification would make German reunification look cheap in comparison.