They are emmigrating illegally and ANY country in the world would treat them the same if they were found to be crossing borders illegally
Um, no. Refugee/Asylum seeking status is recognised under International law. While the country is not obliged to accept such people crossing their borders (though technically a refugee must declare their request for asylum in the first neutral country they enter) they are also not obliged to return the refugee's to their native country.
Mind you, you have to wonder at the intelligence of those who flee North Korea for China. It's not like China's record on human rights and similar is any better. Considering theres a fair sized belt of neutral, UN owned land between North & South Korea, you'd think it would make a far easier and safer option.