The most important element of Christof’s speech would have to be proving how the disaster of Truman’s disappearance would not happen again.
There are several factors Christof must consider. First of all, there was a growing movement in support of freeing Truman. What Christof wants to do might not even be legal. Also, after what happened with Truman, there might not be an audience for it.
The largest obstacle to a sequel to The Truman Show would be Truman himself. When Truman found out what had happened to him, he felt betrayed. His whole life was a lie, and everyone from his parents to his wife was an actor. Since Truman escaped, he will likely be a very vocal opponent of any sequel. He will not want the same thing that happened to him to happen to someone else.
Assuming you can overcome public opinion, legal issues, and Truman, there are other things to consider. Your investors will wonder why they should risk it again, since Truman escaped. How would you prevent that? Obviously, the world would have to be more realistic (with no fake elevators). There would need to be tighter control of the cast. One option would be to use an entire cast of people who, like Truman, did not know what was going on. That would take forever, because you would have to start when they were babies or young children, and who wants to watch babies?
What Chrisof wants is realist plots, and not scripts.
We've become bored with watching actors give us phony emotions. We are tired of pyrotechnics and special effects. While the world he inhabits is, in some respects, counterfeit, there's nothing fake about Truman himself. No scripts, no cue cards. It isn't always Shakespeare, but it's genuine. It's a life.
Christof's best bet is to just do a traditional reality show where all of the people know what they are doing and consent. It might actually be interesting to get a bunch of people to agree to live in a fictional, self-contained town and film it. This would produce the realism that Christof wants, because after all most of the characters in The Truman Show were actors, so the whole thing really wasn't real.