That means someone else brought in a HUGE amount the same day. This poor chap was just a distraction.
It could be that,or it could be many of things. No need to jump to conclusions when there could be many other explanations.
We probably will not find out exactly what happened. However, how did the Thais know? If Thai LE knew about this guy why did they let him through to Korea? Kind of reminds me of the Micheal Connell incident a few years ago. Another scapegoat mule in my book.