Not that i am saying I am right, but I have a hunch what he says in the audio isn't orders, but him getting their guard down and luring them back from the direction they were walking. If he said there was a problem, that could have explained his behavior in their mind. There are convicts who convince corrections officer to throw away their lives, someone who is confident, articulate and charismatic could easily influence a child/teen. The person in the audio doesn't sound demanding or even really panicked. In my mind he sounds like a salesman. He is a little anxious but his few words that are in the recordings roll, they start out deep and soft and roll out to carry his voice (most likely due to the noise of the water that garbled the audio a bit). He could have been in the woods in the direction they were walking to, parked down where they came from and then approached them while they were on the bridge to kinda back them into a corner psychologically. Police use this technique in interrogations.