Even though Qianye Guiyi also knew the Yin-Yang Talisman, in theory, he shouldn't have been a target of the stone statues, but he had previously rescued Anxin Renlong, who didn't know the Yin-Yang Talisman. Qianye Guiyi, implicated by him, definitely would not uncover this secret.
And even if they scurried around like rats with their heads chopped off being chased by stone statues, they certainly wouldn't leave that easily, leaving all the benefits to Tang Yi.
If they caught up later and discovered the Jade Stone suddenly left here, what then would happen?
At that time, it might lead to infighting between Qianye Guiyi and Anxin Renlong. And the tomb of Abe no Seimei is clearly much more dangerous than the outside. With two less people causing trouble, or even one less, the risks for Tang Yi would decrease significantly.