When Shin announced that, Kerin was completely shocked. He never had any ambition of becoming a king. All he wanted was a post from where he could serve his own people and help them properly.
It wouldn't be an exaggeration to tell that the current property of Loria in financial fields was thanks to Kerin and is wise thinking.
'Yes, he would be the best one to rule for now.'
'Rather than making him a foe or killing him, it would be best to pull him towards my side.', was what Shin thinking.
Well, it was not that he just randomly decided this. Of course, the decision of leaving him to handle the kingdom, for now, was made instantly, the process of thinking wasn't that simple.
Earlier when Shin was surprised to see that a human came forward to converse with him, he had analyzed and had taken a look at his profile.