Without having seen the bodies, Sephiroth can only decide it must be a mistake. Noctis said it had been secondhand information.. saying so again was likely a bad idea, so he doesn't. It's obvious even to him that there was a considerable emotional attachment, prodding at it when it didn't really matter was pointless.

Of course Charlie didn't bring them back from the dead. Dead was dead.

"Bring him a fish," he suggests instead, gaze shifting away and to the forest.