Tony's mouth opened to protest, then just turned into a scowl for that look Nick gave them, realizing he really was a lost cause. Tony just went back to rebuilding his pebble structures, keeping his peace of mind to himself; there was no way they were going to run out of air. The train crashing into them caused enough of a shift the tell him there was still a lot of movement in the rubble. They weren't packed in here; there were air passages. Really, their survival depended on whether the rescue crew could get to them before they killed each other. And they were coming-- Tony didn't need to waste a wish on them. He had people that would unearth the whole underground to get him out to make sure he kept signing checks. If he had just one wish, it would be an easy choice.
"Okay, here's the flip: what's something you would rather die than see happen?" he asked, just glancing up at the other two before returning to his work.