Subspace pollution won't dissipate on its own, just as justice won't assert itself — Vanna knew this all too well after combating the deep and twisted shadows of the world for so many years.
If this church had been polluted by subspace and all the nuns guarding it had already been defeated by the pollution, then whatever originally invaded this place wouldn't just vanish on its own — considering the eerie "echo" of the nun in the main hall of the church and the unusual atmosphere throughout the entire Sixth District, it was clear that the doors of the Underground Sanctuary didn't keep out the invaders from this place, so...where had the invading subspace forces gone now?