They were always an obstacle to Camino, let alone in urgent times. Shouldn't they be hitting them when they were down at a time like this?
"Commander-in-Chief Leng, I am indeed Sanji. If you don't believe me, you can ask Leader Chi Yang when he gets back. He boarded the ship an hour ago and should arrive at Jiang District's port in about an hour."
Sanji had already said this, so there was no reason for Leng Jinpeng to not believe him.
"Then I shall thank you, General Sanji. I, Leng Jinpeng, owe you for this. If you're in any trouble in the future, as long as it's not illegal, I'll do my absolute best to help you."
Leng Jinpeng knew Chi Yang must have helped Sanji too, so that was why he was conceding. Even so, Leng Jinpeng was willing to thank Sanji.
Because Sanji kept this in the dark, the head of state of Mustapha would not ask for an explanation from Camino. Hence, the general would not punish him.
Thus, he was willing to owe Sanji a favor.