Why did Qin Qiong Weichi Gong become a goalkeeper?

Why do people choose these two men as door gods? It is said that the goalkeepers of Qin Qiong and Weichi Gong in the late Sui Dynasty, Yang Guang, the emperor Yang Di, were fatuous and ignorant, which led to world chaos. In 6 17 AD, Li Yuan set out from Taiyuan to attack the Sui Dynasty. In Huoyi, Yanzhou (now huozhou city, Shaanxi Province), Li Yuan led his troops to fight against Song Laosheng, a general of Sui Dynasty, and finally killed Song Laosheng. Liu Wuzhou took advantage of Shanxi's emptiness and occupied Li Yuan's Shanxi lair. In 6 19 AD, Li Shimin was ordered to return to Shaanxi to fight, and then came to Huoyi. Liu Wuzhou ordered the fire city to be guarded, while Weichi Gong was ordered to guard the pass in case of attack. So, Li Shimin sent Qin Qiong to fight Weichi Gong, and they couldn't tell the outcome, so Li Shimin wanted to subdue Weichi Gong. But Weichi Gong said that only when Liu Wuzhou died would he submit to the Tang Dynasty. As Li Shimin couldn't kill Liu Wuzhou soon, he found a man who was very similar to Liu Wuzhou and gave his head to Weichi Gong. Unexpectedly, Weichi Gong believed him and joined the Tang Dynasty. When Li Shimin lived in Huoyi yamen, he always dreamed that two headless people were pestering him. They are very much like Song Like and Liu Wuzhou. Xu Maogong put forward a plan and said, "Because your master has killed the man who looks like Liu Wuzhou, you can send Weichi Gong to guard the yamen at night." Sure enough, Liu Wuzhou's ghosts no longer harass Li Shimin. However, another Song Laosheng came to harass, so Xu Maogong added: "Song Laosheng, a general of Sui Dynasty, was loyal to Qin Qiong and admired him very much. Maybe he can let Qin Qiong guard the yamen at night to get rid of it. " So Li Shimin sent Qin Qiong to the yamen to watch at night. Sure enough, Song Laosheng stopped harassing him. The story spread to the people, and later people began to put portraits of Weichi Gong and Qin on their doors to prevent ghosts from causing trouble. Therefore, Qin Qiong and Weichi Gong became door gods.