Gods were never meant to stay in the realm of man, be it a physical or metaphorical presence for humans could only be humans without the presence of gods who dictate how one should leave.
Byung held the key to the gates of this world but his heart had weakened over time due to his powerlessness.
The power he possesses, the power that's been sealed away.
But for how long can that seal hold if whatever lies beneath can grant the user what they sought?
Each moment of despair, sadness, and anguish weakened the seal tremendously, Byung had become one with it.
The key couldn't be found individually anymore nor could it be separated from Byung after the ritual of Ki-Tae.
Byung was a high threat but they still had time.
The key had been sealed, there was nothing to worry about, at least for now.