When Ren Xiaosu heard Yang Xiaojin talking about the Pyro Company, he quickly processed what she said. That was because a lot of information was contained within that short passage of words.
Xu Xianchu obviously did not know this information about the Pyro Company. That was to say, Yang Xiaojin had far surpassed Xu Xianchu, who was a soldier of the private army, in terms of gathering intelligence.
Moreover, Yang Xiaojin had mentioned, "Perhaps only the core personnel of the Pyro Company know what really happened there." Why was she so sure that only the core personnel knew about it rather than the entire Pyro Company? Yang Xiaojin must have sought out information from some of the Pyro Company's members before but to no avail.
Ren Xiaosu felt that Yang Xiaojin couldn't have managed that alone. It was just like how he didn't know how many strongholds had been built by humans until now, with the highest number that he had ever heard of being Stronghold 178.