Why did Liu Bowen say nothing in his later years?

In the eighth year of Hongwu (1375), Liu Ji caught a cold. When Zhu Yuanzhang knew about it, he sent Hu to see the doctor. The physician made a prescription, and he came back to decoct the medicine according to the prescription. He felt as if there were some uneven stones crowded together in his stomach, which was very painful. In mid-February, Liu Ji came to see Zhu Yuanzhang when he was ill, and told him tactfully that Hu had come to visit the doctor, and he felt even more uncomfortable after taking the medicine prescribed by the doctor. Hearing this, Zhu Yuanzhang simply said some words of comfort to let him relax and recuperate, which made Liu Ji quite chilling. In late March, Liu Bowen, accompanied by Mclynn Killman Liu and Zhu Yuanzhang's task force, left Beijing for home.