Why can Les believe the universe is still being created and expanding?
Because God is infinite, there is no outer shell or limit to His creation. If astronomers say the universe is still being created and moving farther outward, that fits the Word of God, which says the worlds were framed by His spoken Word and came from nothing.
Les teaches that faith is not blind but documented by the Word of God, and believers can understand that the worlds were framed by the Word of God. He explains that God spoke it, and it came into being. If astronomers say everything is still being created and still moving further and further, Les can believe that because God is infinite. There is no putting an outer shell on God's creation, so the things seen were not made out of things that appear.