Originally, Jimmy didn't intend to reveal himself directly, but there was no choice. That buyer was preparing to leave. If he didn't step out now, once they left, he had no hope of intercepting them.
Because what the other party said earlier was very clear: there was a plane coming to pick up people and bring money, Carlos and his people would send someone to get the money, and this buyer would no longer appear. By that time, even if Jimmy captured the pilot on the plane, he wouldn't be able to know much about the inside details. At most, he might find out which airport they would land at, but as for where these people would be taken, no one knew.
