"Yes, I thought about it, it's why I went on the trip in the first place. The soil sample was for extra research." So Istredd put some consideration into it before he made the plan. There was some stopping involved. He knows that just means he was plotting and lying as soon as the tremors started, but he had a theory.

He puts a hand on Lucifer's arm, not pushing him off, just touching him as a grounding effort for them both. He knows this all comes from a place of concern so it's why the anger doesn't bother him. Kyle's reference to Lucifer being a creature of rage was brushed off. He isn't worried for himself.

"Tell me what the better idea was. How else could I have proved it? Using a native would have killed them. We needed to know for certain."