She asks, what is on the surface, a pretty inoccuous question. Was it difficult terrain? Really? She pointedly includes from the bridge to where they were found... it's a fishing expedition and he bites.
She doesn't ask for details. She doesn't poke or prod. Unassisted, and unaided, he traces the route they took and explains the difficulties with the obstacles they came across. To accent his own point, he adds that it's not normally a place people would go.
It's pretty honest. It's pretty forthright. It's from someone intimately involved in the case who likely knows exactly what path they took. He also has a vested interest in letting any information out, and is careful in what he divulges.
Maybe if he had a do-over, he'd say something different, but there's no reason not to take it at face value. He doesn't go into what he thinks happened and where. He is careful to guard that. They may have, in fact, not crossed the creek alive, and his hesitation with details may be an indication of that.
