He's truly unsurprised at what certain passengers will tolerate, how they excuse their infuriating complacence by claiming people need to have fun to stay sane and then do nothing but indulge themselves.

All Natsuno says, though, is: "Whatever."

None of what he said is secret, but does hate being provoked into it. He turns to leave without another word. Gotta change out of the bloodstained shirt, anyway.