Usopp telling Nami to lie about Luffy becoming Pirate King is regression no matter how you slice it
Usopp will do that for Luffy, but he did not want Nami to put her life in danger. You think Luffy would have accepted that?
The whole point of Sabaody and the time skip was to establish that the lives of the crew should be put before anything else. The Straw Hats almost died, and Ace did die for Luffy to learn this lesson.
There is no version of the story where Luffy or any of the Straw Hats would accept Namis death for standing up for Luffys dream, while Usopp cheered her on.
I guarantee you, that if Luffy was shackled in seasstone, and in the same scenario, he would have told Nami to lie also.
The Straw Hats have evolved beyond that of a Pirate Crew. They are a family. Luffy watched his brother die first hand because of his pride. He damn sure would not wanna see that happen again.