With Dao Kong's status, once he left Black Ink Planet, he would return straight to the galaxy where the forces of power from the four Great True Worlds were stationed. Through that place, he could return to True Morning Dao World, but should he..? He was not really in a hurry to leave. He could also head to Divine Source Star Ocean.
With these two as options, Su Ming would naturally choose the latter.
Even if he really wanted to return immediately to True Morning Dao World… his Ecang clone still required a large amount of Divine Source to grow stronger and devour the other nine Ecang souls, and the best place to obtain Divine Source was naturally the mysterious and enigmatic Divine Source Star Ocean.
After all, that was the place where numerous Gods died or fell asleep. That's why the Divine Source Su Ming needed was in that place.