What suggestion was Passepartout prevented from making?

Passepartout was prevented from suggesting the passengers walk across the dangerous bridge, and afterward, the train could follow.

"Yes, all aboard!" repeated Passepartout, and immediately. "But they can't prevent me from thinking that it would be more natural for us to cross the bridge on foot, and let the train come after!"

But no one heard this sage reflection, nor would anyone have acknowledged its justice.