Why did Matthias have to be chosen to replace Judas?

Les explains that Jesus, speaking of the Son of Man sitting on the throne of His glory, told the eleven they would also sit on twelve thrones, ruling the twelve tribes of Israel. Judas had abdicated his spot, leaving it empty. Peter was all uptight because he thought the King was coming at any moment, and they could not have twelve thrones filled with only eleven. So Peter's first item was to get a replacement for Judas, and they chose Matthias. Since they were going to rule twelve tribes, they had to have twelve men, and Matthias filled the slot Judas left open. Les says this all shows God was promising the nation of Israel an earthly kingdom, and then Scripture moves into the Book of Acts.