Gordolf talks about how truly amazing the performance of the Shadow Border is, and how it will be a technological revolution when introduced to panhuman history, but Nemo shoots down the notion.
Nemo:
That's an unlikely scenario. On a planet where human beings are the apex species, this ship cannot function.
Due to the blank nature of the earth, my Noble Phantasm, Sion's pseudo-spiritron armor, and the techniques of Hephaistos and Chaldea combined, it manages to function.
The existence of the Shadow Border is only a confirmed fact until we defeat the "Alien God".