I just think that its odd that he hasn't used a shadow clone in his battle vs Delta. I think it may be because his real body is spying on Koji and his clone is fighting Delta.
It's plausible he found Koji. It's kinda weird that his SM can detect battles and people across the ocean from the turtle island while his RSM is incapable of sniffing out Koji who's no more than a couple of meters far.