To call a group of our fellow humans "a sort of new species" - as the author does - is offensive, no matter who the target.  That legitimately offends my sensibilities, as I consider myself to fall under the same umbrella as North Koreans - that of humanity at large.  As you stated yourself, these people are physically different from others due to a lifetime of malnutrition, NOT a genetic evolution, which would be necessary for a new species to emerge.  Also, using the term "dwarf", which is a colloquial term for a medical disorder, is simply inaccurate, and hints at the superiority bias of this author.  The rest of the piece follows a similar tone, and to me does no good in bringing us to a more civil position with North Korea.