Andrea tried to think of the most persuasive argument to win over the detective, something that didn't appear defensive, like they were concerned about looking guilty. She needed to undermine Celine's credibility without being too obvious, lest they think Andrea and Kyle were worried about what she might say.
…Which is to say, they were worried about what she would say, but only because they were afraid of what further lies she would spin to save herself at the cost of condemning Kyle.
Her strongest argument was demonstrating that Kyle was more valuable to them free and working on the case than rotting in jail. It was in their interest to keep him at liberty if they wanted to catch the true culprits.
