"You know we can't do that. Everyone's lives depend on things staying the same."

Because time is, ultimately, set in stone. No one can change time, not without changing the whole universe. Causality coming crashing down, like dominoes in an endless chain - and for the sake of everyone that fought to live in this timeline, they cannot let that happen.

"If there's something you want to talk about, we can do it after we go back." Because if Sayo didn't stop right now, he probably won't go back.

Not all Saniwas are soft-hearted enough to crack under this sort of pressure.