Yeah they announced it a few days ago.
http://en.koreaportal.com/arti…p-nation-s-upcoming-k.htm
Basically they decided it was in his best interest if he keeps training for a little bit longer.
You just could tell how uncomfortable he was on stage when the live round started. But PSY knew that you can't hit the jackpot if you don't have a Japanese member in your group and Keiju choosing JYP was kinda unexpected