Why did Qu Jianghe give the skull to Meng Chuansheng in "The Eleventh Floor Lost"?

The overall score of the missing eleventh floor is 2023 /

Qu Jianghe handed over the skull to Meng Chuansheng for the purpose of submitting the nomination certificate. Qu Jianghe directed and acted in a skull theft case, and then he gave the skull to Meng Chuansheng. Qu Jianghe did this to gain Meng Chuansheng's trust. Qu Jianghe and Meng Chuansheng are righteous brothers. Although they are not blood brothers, their relationship is stronger than that of blood brothers. Qu Jianghe was always bullied when he was a child, and it was Meng Chuansheng who helped him out. Although Meng Chuansheng and Qu Jianghe are brothers, they are afraid of each other because they chose different paths.

When Qu Jianghe investigated the 919 case, he found a pair of invisible hands stopping him, and Qu Jianghe couldn't carry out his work smoothly at all. In order to investigate the truth, Qu Jianghe had no choice but to blackmail himself and break into Meng Chuansheng's interior to get the evidence. Although Meng Chuansheng kept saying that he regarded Qu Jianghe as his real brother, he kept holding him back. Qu Jianghe knew that in order to gain Meng Chuansheng's trust, he had to show some real evidence, so he handed over the key evidence skull to Meng Chuansheng.