In the process where the Ghost King summoned the Netherworld Commander Bull Head with the Samsara Authority Token, Shen Yuan had numerous opportunities to interrupt the summoning, but he chose not to do so.
The main reason was that Shen Yuan had already sensed the power of the Incense Offering Divinity Path contained within that Samsara Authority Token, and the first force drawn by the Ghost King was also the power of incense offerings faith.
Shen Yuan, with the Gods Purging Divine Power at his disposal, could suppress even a Divine Monarch descending to the mortal world.
Moreover, if a deity of this era manifested with a realm that exceeded the limits of the Spirit Refining Stage, they would inevitably suffer backlash from heaven and earth, even with the protection of water monsters, so Shen Yuan was not at all worried about the Ghost King's contingency plan.