Because it is simple. It's not a complicated situation.
Of course not saying it's without its difficulties. He has a name, number, its a start.
Maybe pay for a person search. Or hire someone. Maybe even banking details. A quick Google gave me hundreds of options. Should he have too, probably not. But it is what it is.
He has numbers. Regardless whether they work. Legally the phone companies would have to give up information if it went to court. Perhaps it needs to go to court to acquire the information.
I'd fill out what information I had and state difficulty in tracking him down if it'd an issue. They may even suggest further action.
Got to be worth a shot? Better than buying another setup. Which is insane.