Cui Lao was a senior figure in the Ling Family. He had been a loyal servant to the Ling Family for over 30 years and was also the leader of these men of sacrifice. If even he got on his knees to kowtow to Ling Yun, how could all these men of sacrifice not do the same?
Moreover, Ling Yun didn't just save the entire Ling Family, he also saved the lives of the 36 men of sacrifice. They wanted to kowtow to Ling Yun quite some time ago but didn't manage to find the appropriate opportunity to do so. Now that Cui Lao took the lead, there was no need for a second calling, all of them got on their knees almost instantly!
It could be said that throughout the entire Ling Family, only Ling Lie had received treatment like that before. Even the current head of the family, Ling Zhen, hadn't received a mass kowtow from all the men of sacrifice.