There were many reasons to cough, with the most common being illness.
Cold air harming the lungs was one of the most lingering illnesses. Even an expert of the Divine Domain would find it very troublesome.
Shang Xingzhou had no idea that the White Emperor would be coughing throughout the following years and months, coughing for many years.
But he did know that the White Emperor had suffered significant injuries, just as he had.
The two Angels of Sacred Light and Madam Mu were extremely powerful opponents.
He and the White Emperor were the strongest of the current era, but they also had to pay a certain price.
That he chose not to exercise all the options available to him at this time was based on this reasoning. It was also because he knew that Chen Changsheng and Xu Yourong would not support him. He and the White Emperor could alter their wills according to the situation at any time, but that young couple would not.