Senior White had already proven the feasibility of cutting himself in half in the Heavenly Tribulation Realm. He had left one half to transcend the tribulation while the other half went to the main world to play.
As long as half of his body was still in the Heavenly Tribulation Realm, there wouldn't be any problems with the process of transcending the tribulation. The other half of his body that had gone to the main world to play wouldn't be forcibly pulled into the Heavenly Tribulation Realm by the laws of the world. Unless the other half of his body that had stayed in the Heavenly Tribulation Realm was turned into ashes by the heavenly tribulation, the other half of his body that had stayed in the main world would be pulled into the Heavenly Tribulation Realm again.
