When Hasula was trapped within the World in the Sleeve, he was fully aware of what was happening around him. He understood he encountered an attack that was made by manipulating space. He could predict the possible changes what would occur. Since Su Meng dared to come, he definitely had a way to escape by seizing the various opportunities. The alliance between the grassland and Zuo Dao would be in chaos as Hasula was captured. This allowed the Sword-Enshrining tower to take a breather.
When he thought of these, blood rushed to his face. He felt that he was humiliated as he was filled with self-reproach. If only he felt that he was less proud, he would not think that he could block the strike from Su Meng. He would have chosen to dodge, which would result in a different outcome. Not to say that Su Meng would be completely surrounded, but at least the situation would not be as chaotic.