Po Tian wanted Ling Chou and Chu Ying dead, and Chi Xue felt the same. It wasn't just that they couldn't stand seeing Ling Tian and his direct disciples act so "arrogantly." More importantly, if the two disciples fell, Ling Tian would very likely take Feng Lingzi and the others with him when he crossed the tribulation. Chi Xue would be delighted to see that happen. He and the others believed Ling Tian had taken on direct disciples to protect his friends and family, who were hiding inside the Outer Realm Stone. If Ling Chou and Chu Ying died, Ling Tian probably wouldn't keep Hua Min'er and the others in the God Realm. It would simply be too dangerous.
Indeed, since Hua Min'er and the others were sealed away inside the Outer Realm Stone, they had almost no way to protect themselves. That was why they needed a powerful cultivator to guard them. Ling Tian had chosen Ling Chou and Chu Ying for that role. If those two were killed, Ling Tian naturally wouldn't leave Hua Min'er and the others in the God Realm any longer. He would take them with him when he crossed the tribulation.
That was why Chi Xue and Po Tian both wanted Ling Chou and Chu Ying to fall. They knew, however, that they couldn't make a move themselves. They had already figured out that Ling Tian must have cultivators secretly protecting the two. Even if Chi Xue and Po Tian attacked, they would probably fail—and would also incur Ling Tian's wrath, perhaps even bringing his pursuit down on them. They had no chance against Ling Tian now; they would surely die. With that in mind, they wouldn't act personally.
They couldn't attack themselves, and ordinary cultivators would have little chance of defeating Ling Chou