Mr. Sun couldn't take action himself, Little Princess and Mesmerizing Demon were not strong enough - it was possible to send Sullivan to the Main Altar or Divine Desolate Land for a challenge. Surely, a Ninth Great Realm could attract a Guardian General of the Faith, but in that case, Sullivan would most likely fall. Since this fellow had been well-behaved lately and was handy for Mr. Sun, there was no need to send him to his death.
The reason Mr. Sun had been sitting quietly for three days was that he had gained many ideas about secondary extension powers due to the interaction between his acquired "power" and the previous second power "tool." He had used these three days to integrate these secondary eye powers into a chessboard, which was a set of methods suitable for use in the Great Concealment Realm.