"Su Shenfan is the smartest person, making the least amount of effort for the biggest benefit. When he found out we were going to steal the supreme pill, he knew to adapt to the situation, and switched sides. He clearly wants the pill, but he's still willing to give it to Lian'er. How interesting."
Although part of it was because Xiao Jingyun had courted death himself, Gu Bailu still believed that the biggest reason Su Shenfan had switched sides was that he had to have the supreme pill.
In other words, he had actually been more optimistic of Gu Bailu's chances of getting it.
It was probably during that competition that he realized that she might have the upper hand in the underground palace without spiritual power.
Anyone who knew that there was such a great pill would fight for it.
If someone else was going to eat it, he had to have it too. That way, he could maintain his god-like position.
Su Shenfan was definitely smarter than anyone else.