Shin gazed at the rewards that were placed in front of him as he continued to munch. He had claimed only one of them, the rest still remaining.
[Rewards for the main quest:]
[-> +5 Levels Gain] [claim]
[-> Brothers Of Judgement will join your side.] [claim]
[-> Clue about the Heavenly Wolf Family.] [claim]
[-> System Update.] [claim]
[Rewards for sidequest:]
[-> Become the owner of the Gem of Truth.] [claimed]
[-> Hint about Gem Of Lie.] [claim]
He was now the official owner of the Gem of Truth, so it didn't matter where the gem went. No one would be able to use it unless he lets them too!
It was a bold move from his side and it was precisely because of this that he didn't have any problem with Mike taking the gem.
Furthermore, he didn't want to get on his bad side, after all, he wanted help from them.
Mike was smart, but Shin outsmarted him.