I learned of this tradition when I was in grad school. It goes much deeper than this clown is explaining.
The true translation of the greeting was something along the lines of, “I did not exist until you saw me.”
The act of seeing and acknowledging someone gives them meaning and a place in the world. Try explaining to a six year old the concepts of “existence” and meaning in the world.
I think existential philosophy might be a bit too much for first graders.
More Niels Bohr than de Carte.