The reason Zhao Zheng chose not to retreat was simple: he wanted to show off.
He was quite skilled in martial arts, and he figured that by the time anyone actually fought their way to him, their numbers would be severely depleted. He could then reveal his own formidable prowess, successfully executing his plan to show off. He hadn't flexed his muscles in a long time and was itching for a fight.
However, just as he was preparing to act, someone crashed the party, thwarting Zhao Zheng's grand display.
Chapter 36