You would have to ask whatever spook created the name, which is probably impossible. Different agencies have different protocols when it comes to program and project naming conventions. However, one speculation I saw on Twitter proposed that immaculate refers to the quality of intelligence, and constellation refers to the "constellation" of intelligence platforms and programs associated with the program.I am working my way through the video gradually but does he explain at any point why this program was called 'Immaculate Constellation'. Is it a pun on the 'Immaculate Conception', a title linked to the Blessed Virgin Mary? It just seems odd.