The Xuanwu Gate was too small to accommodate such a large Qin Qiong.
This is a joke. But not entirely without reason. You must know that the Xuanwumen Incident was a sudden coup d'état, and Li Jiancheng's side was completely unprepared.
Of course, Li Shimin was prepared. But, if you think about it, Li Jiancheng is the crown prince and Li Yuan is the emperor. If Li Shimin mobilized soldiers and horses on a large scale inside and outside the imperial city, would Li Yuan and Li Jiancheng not know? Are you when they are wooden people?
According to the Zizhi Tongjian, "In June of the ninth year of Wude's reign, the Turks would set up tens of thousands of horses to ride tun henan", and Li Yuanji took Shimin's lieutenants Chi Jingde, Cheng Zhijie, Duan Zhixuan, and Qin Shubao (that is, Qin Qiong) to send troops to "save Wucheng". Sending Li Yuanji to lead Li Shimin's generals to send troops is obviously intended to divide and weaken Li Shimin's forces. This proposal was put forward by Li Jiancheng, and the intention is even more obvious.
Of these four people, only Wei Chi Jingde participated in the Xuanwumen Rebellion. I don't think the other three betrayed Li Shimin. Because another detail is recorded in the Zizhi Tongjian: before the incident, Li Shimin summoned Fang Xuanling and Du Ruyi, and the two refused to meet with Li Shimin, the king of Qin, on the grounds that "the edict does not listen to the King of Fushi; if he is private now, he will sit dead and dare not follow the teachings". Angry, Li Shimin directly ordered: "If you don't have the heart, you can cut off his head", and if he doesn't come, he will kill his head!
Fang Xuanling and Du Ruyi probably did not want to betray, but they were afraid of the seriousness of the situation and did not dare to act rashly. They then "wore Taoist clothes, entered with no scruples, and respected morality from others", put on makeup and modifications, and sneaked away separately.
Of course, Li Jiancheng and Li Yuanji did not know that Li Shimin was about to launch a coup d'état, but they were already on guard and wary of him in every way. Under such circumstances, Li Shimin did not have much freedom in calling for and not in the coup: he could only mobilize his unobtrusive subordinates, and he could not transfer all the personnel carrying out the same task. Because that's too easy to hit the grass and startle the snake.
The change of Xuanwumen was an absolute risk-taking action, and Li Shimin was absolutely not sure of victory. However, when possible, he still had to do a good job of secrecy, try not to alarm the enemy, and try to strive for a greater chance of victory--this may be the reason why he did not recall Qin Qiong.