Simeon holds the newborn Jesus and says he is a light for the nations. There is something bigger going on here – echoes of a man called out of Ur to be a blessing for all nations. Simeon points toward the reality of the salvation that came with Jesus. He was so sure of it he did not have to stick around to see the salvation fulfilled.
Which raises the question: saved from what? Simeon had far more in mind than the modern Western idea of salvation (meaning going to heaven). This salvation was about things happening here and now on this earth.