I wouldn't say anything. He is making the choice and will face the consequences.
You aren't there to help rehab do their job. They have lots of experience with folks trying to keep their phone and I'm sure they will handle it the right way.
Learning to abide by rules (even if they resist at first) is part of the process of recovery. It is as much a test to him as it is a breaking of their protocol.
What will be will be
