Why would Yuan Shu let Sun Ce go to Jiangdong if he knew he was brave and good at fighting?

In "The Romance of the Three Kingdoms", it is recorded that in order to seize the land of Wu, Sun Ce dedicated the "Jade Seal of the Kingdom" captured by his father Sun Jian to Yuan Shu, borrowed some soldiers and horses to return to the land of Wu, and then took the opportunity to escape from Yuan Shu. . There is no such record in Chen Shou's "Three Kingdoms", and Sun Ce did not present the jade seal to Yuan Shu. So why did Yuan Shu release Sun Ce back to Jiangdong?

First, the feeling of guilt. Yuan Shu twice promised to give Sun Ce territory, but he broke his promise twice. At first, Yuan Shu had promised to let Sun Ce serve as the prefect of Jiujiang, but in the end he made his confidant Chen Ji the prefect of Jiujiang (Xu Ce was the prefect of Jiujiang at the beginning of Shu, but later changed to Danyang and Chen Ji). Later, Yuan Shu wanted to attack Xuzhou, but because his army was short of food, he borrowed food from Lu Kang, the prefect of Lujiang, but failed. Yuan Shu had the idea of ????eliminating Lu Kang.

It happened that one time when Sun Ce went to visit Lu Kang, Lu Kang only sent his chief clerk to deal with Sun Ce. Sun Ce had always held a grudge against Lu Kang, so Yuan Shu took advantage of Sun Ce's hatred of Lu Kang and sent him there. Before Sun Ce went on an expedition, Yuan Shu said to Sun Ce: "I used Chen Ji wrongly in the past, and every time I regretted that my original intention failed. If you are healthy now, you will have the real Qing of Lujiang." After Sun Ce received Yuan Shu's "blank check", he quickly conquered Lujiang. But this time Yuan Shu changed his mind and asked his old official Liu Xun to serve as the prefect of Lujiang (Shu reused his old official Liu Xun as the prefect).

Second, he distrusted Sun Ce and wanted to use Jiangdong's forces to get rid of his big trouble. The powerful families in the Jiangdong area were all mixed up, making it not an easy "bone" to chew. At this time, Sun Ce's power was not strong enough, and he had only one ability. Therefore, when he decided to go to Jiangdong to help his uncle, Yuan Shu only gave Sun Ce "military wealth". More than a thousand, riding dozens of horses.” And because "the generals Qiao Rui and Zhang Xun admired him with all their hearts" he was afraid that Sun Ce would poach him, so he wanted to use Jiangdong's power to get rid of Sun Ce, so he let Sun Ce go to Jiangdong.