Then, he looked at Adam and said, "Before we leave this place, I have to get what I want first. Otherwise, even if you kill me, believe me, you will not get your sister."
Jason already had an idea that he possessed an advantage in this situation. It was very clear that Alicia was very important to Adam. And the same to him, that human was important to him.
So, they could have gone ahead and made an exchange. But previously, believing that he was going to be capable of dealing with Henry and the others, he decided not to talk about this matter.
As long as he could get what he wanted here, he could go ahead with the plan that he was having about Alicia. But right now, it seemed that it was going to be impossible. The only thing that could happen was for him to get one while losing the other, but he could not get all of them together.