There was a high chance that the Liu Jie in the contract had some relation with his mother. Another factor that supported his guess was his mother handing him the contract for safekeeping. With her long absence, he had a long time to think through some things and one of those things was the contract and why his mother handed it to him for safekeeping.
That reason didn't make any sense, considering his cultivation realm. Yes, he was one of the youngest core formation experts around, but that wasn't out of talent, but rather his circumstances, and as a core formation expert, while he was strong in certain circles, in the grand scheme of things, he was just a strong ant.
His abilities were insufficient to act as a keeper for a contract signed by a rank two organization, a rank three organization, and a sixth-stage palace realm expert. He had no business handling their contract.