My guess was that the Apostles were never part of Marisbury's plan to begin with.
We know Olga being summoned was a fluke. We know the Apostles were summoned by the Alien God, and their purpose was to summon Olga, guide Chaldea, and guide the Crypters. We also know that the Crypters only got revived and the LB arc only kicked off because Lev threw Olga into CHALDEAS.
So basically, evidence points to the idea that had Olga never been thrown into CHALDEAS none of this ever would have happened. Marisbury's plan would have gone off without a hitch, and this obstacle of the Lostbelts/Apostles/Olga never would have slowed it down. The Apostles wouldn't have had a goal had Olga not become the Alien God because the Apostles' existence is preceeded by Olga.