Tan Xiuteng was, after all, a supreme god, and one approaching the level of an invincible supreme god. Naturally, he knew that at their level of cultivation, many matters had to account for the "Heart Demon Tribulation" during the millennium tribulation.
If he were acting on his own to kill the person before him without orders, that person would, nine times out of ten, never let him off. If that person were broad-minded, it might be fine, but if not, they would inevitably choose to kill him to eliminate future trouble and avoid the risk of triggering the Heart Demon Tribulation during their own millennium tribulation.
"Fortunately, I was acting under orders."
Chapter 4013