I’ll bite, why do you think so?

There have been defectors in the past, they were treated pretty well by all accounts. It beats working for the US military, especially the kind of US military that tend to be stationed in South Korea. He was apparently being held for disciplinary action, so probably did something horrible like report another US soldier for sexual assault of the locals.

I will admit that crossing the border can be risky between minefields and soldiers from both sides, but as he seemingly made a safe crossing he should be okay.