Partially that scheme seems to be an attempt to engage DPRK in some kind of dialog to prevent an unstable dictatorship with nuclear weapons and a lot of artillery that can reach Seoul from causing bad damage.

But given that utilising or even tolerating slave labourers on the ground in democratic nations is such a shameful thing, it might be better to actually let DPRK be completely isolated from global economy and not allow any of these arrangements. Even if that results in more misery for the people in DPRK.