After hearing the full story, Rod realized that the one referred to as a "cancer" by the others was none other than that Iron Mask, Manolo Bana.
From the very beginning, this individual had been looking for trouble with Rod. Initially, Rod thought it was because he had offended his son, Habulin, but later he found that the higher-ups obviously had more important things to worry about.
Manolo Bana's extreme efforts to label himself a Doomsday believer were an attempt to strike at Guardian Qingyu who protected him.
He was heavily suspected at the time; the Redstone Village case had made a significant impact and Qingyu had used her Guardian privileges and reputation to vouch for him.
If Manolo Bana managed to tarnish her name, then naturally Guardian Qingyu's reputation would be damaged.