Caine wasn't influencing Jax
I've seen theories that Caine was altering Jax's thoughts to make him press the red button, but I disagree. I think that was fully Jax's choice.
First, there's no need for Caine to influence him. It's already in character for Jax. Prior to this episode, I was even thinking that if Jax got the opportunity to exit, he wouldn't take it. See my short analysis about it here.
Second, remember that Jax's panic attack was already beginning as they were walking down the hall before entering the console room. It had been building long before he pressed the button. It wasn't sudden like the veganism and stupid sauce were.
Finally, and I think most importantly, it would be out of character for Caine to influence the adventure like this. He coded two endings: the Good ending and the Shrimp ending. He made it possible for them to make the other choice. In fact, the point of the adventure was for Caine to prove to himself that the humans wouldn't abandon him. If he forced the result, it would mean nothing.
I've seen some ask: "if Jax wanted to stay, why would he have gone along with the plan until the end?" I'd argue that Jax didn't want to go along with the plan. In fact, he was going to completely sit this one out:
I can think of 2 possible reasons why he eventually chose to go along with it:
Jax believed this was just another twisted adventure for the majority of the episode. He started panicking towards the end when he started thinking, "but what if it's real?" And he couldn't let that happen.
What I think is more likely: Jax wanted to believe that he would willingly leave the circus. Of course he wants to leave! What human wouldn't choose to leave if they could? So he goes along with everyone's plan, because that is what's expected. But as it drew closer, Jax's fears about leaving caught up to him. This caused his panic attack, which led to him frantically pressing the red button.
