You prefer that he should call the Police and then imagine the joy when the scammer's mother would have when she would be receiving the call from a police offi

You prefer that he should call the Police and then imagine the joy when the scammer's mother would have when she would be receiving the call from a police officer telling her "we placed your son under arrest for crimes A, B, C and money laundering and he's looking at 5-10y".. imho he did that kid a favour he didn't deserve. If you ask me he saved that kid's life.