The Arrivals

Even though the main reason on the surface was because of the high possibility of the involvement with the death of so many civilians in battle, another part is also because of his own selfish desire. 

He didn't like this person.

Back then, he ignored Kuang Shen because he felt that it was a hassle to take care of this person. The situation was not right and there were many people around Kuang Shen who protected him. It would be hard to deal with him when he paid a brave visit to him. 

Not to mention, he had good relationship with Traveling Doctor Liu because his grandmother is his junior or senior sister. The two of them always bickered about who would be the senior and who would be the junior, so Long Qian Xing was not very sure.

For the sake of Traveling Doctor Liu, he ignored Kuang Shen and only monitor and intervened when it involved Fei Yang Kingdom's interest.