While the human civilians are willing enough to get flown up those meat processing ships like the cattle they are and even sing the One Piece opening on the way there (it was awesome though, not gonna lie), the giants just live on their daily lives uninvolved with the atrocities their military forces have done outside of that ship.
Sakurai should listen to Tonkotsu's voice in his head and only focus on killing their soldiers and the ones involved in the harvesting process.