Asim did not like Sana ever since he realized that she is a flipper who flips according to convenience and also when she said she wasnt that upset with Asim's "fake" elimination.
He was also upset with Arti when she constantly tries to add fuel to fire and pin point him in everything.
Arhaan just used it to further divide that's all.
Now coming to the task, its a process, Asim's coming through is the end process. If Arhaan's cave had been filled up more like Asim's , people from his group would have been busy trying to help him to clear his cave , they would be distracted both in manpower and strategy.
Look at this pic
Asim's was packed like this for many layers, Arhaan's was comparatively lesser. Arhaan did extremely well , in fact brilliantly so did Khesari
I had told this before, that Sid S does not listen and that's his major flaw. He thinks its his way or the highway.
I for one am very happy if its Asim vs Siddharth, I didn't want him to leave the group this early as there are many people still left but its still ok