Is “He distinguished gratitude and grudges clearly, repaying both kindness and enmity” true?

Records of the Three Kingdoms, Book of Shu, Biography of Fa Zheng records that after Fa Zheng gained power, he repaid every favor and avenged every slight. Some advised Zhuge Liang to restrain him, but Zhuge Liang, considering Fa Zheng's great merits, did not investigate.