Originally, if a suitable vessel was unavailable, Ishiki had a backup plan:
to secretly observe the members of the Otsutsuki clan descending upon the Shinobi World, wait for them to clash and mutually weaken each other either with Uzumaki Naruto or Kaguya, and then seize the opportunity to make his move.
In fact, what Ishiki hoped for most was that one of the descending Otsutsuki would be heavily injured by Uzumaki Naruto and Kaguya, allowing him to successfully capture them. Under such circumstances,
Chapter 321