Have you read the speech from Kim Jong Un that prompted the trip? There's a bit of the military worship and grandstanding you'd expect, but it's shockingly progressive. Besides pushing for reaching global standards in education, science and technology, he's actually calling for peaceful discussions with South Korea about reunification, and removing the barriers for that.

Kim Jong Un has barely been in power for a year, is not even thirty, and was educated in Switzerland. He's also a bit unknown, in that he was fairly well hidden from the world (seriously, it's kind of frightening). There is an actual, real chance that he wants to push for a peaceful reunification, something that would be amazingly good for the world. If he really wanted to do that one of the huge barriers is how polarized the two states are, both in terms of attitude towards each other and in terms of existing infrastructure. If reunification were to happen today it would probably destroy South Korea's economy, so if Kim Jong Un really wants peaceful unification he has to work to close the gap.

Which is why someone who doesn't want to do evil may be compelled to explore this option.