same question, spoiler is welcome :3
Because he was assuming that Dokja was our protagonist.
can u explain that.. im stupid
He knew about Joonghyuk and was assuming that he would be the representative so when he heard that the representative was actually Kim Dokja someone who he never heard of before he was confused for a second. And later when he pretended that he hasn't heard of Joonghyuk before Dokja knew immediately that he was lying and planning an ambush.
OOOOOHHH OKAY THANK U SM!!
why did he make that face when he heared the name kim dokja though