Even the second Divine Skill of Earthly Destroyer, the God's Purging Edict that manipulates the origin of Incense Offering Divinity Path, can't allow Shen Yuan to override two major realms and order a Demon King at the Spirit Refining Stage.
What truly allows Shen Yuan to temporarily restrict the Giant Clam Water God is in fact the River Ji Dragon Seal associated with the River Ji Incense Offering Divinity Path in his hand.
All the power of the incense offerings accumulated over ten thousand years by River Ji converges into the River Ji Dragon Seal, and even the divine position of the Giant Clam Water God is subject to the control of the River Ji Dragon Seal.
Shen Yuan restrains this Spirit Refining Demon King before his eyes by wielding the God's Purging Edict through the medium of the River Ji Dragon Seal and mobilizing the vast power of the incense offerings.
But that's about it, the gap of two major realms makes it impossible for Shen Yuan to issue a second Imperial Edict.