I think "meaning" has also a different interpretation. It can mean something like important, valuable, or that it matters. Something can be experienced as meaningful. That's why for a Christian, a story about finding God would be moving, because they see meaning in having a relationship with God. For an atheist, a story about expanding human knowledge about the universe might be moving, because they see knowledge as meaningful. In this interpretation, life is meaningful. In this interpretation, meaning is something that can be studied by psychologists.

Obviously, when you confuse those two interpretations of "meaning" that you get Eliezer's "one true objective morality to be gloomy and dress in black".