Been down this road 3x with my daughter and heard it all. She put zero effort into it and got about the same out of the experiences. Of course to hear her tell it at the time, all three places were bad rehabs and she was bored out of her mind. Reality was, she was not ready to be done. She relapsed within hours of returning home.
It took me a long time to accept that it 's my daughter's addiction and her recovery , or not. With the benefit of hindsight, I strongly recommend that you do not allow him to return to your home. Give him the gift of dignity to own his recovery or not. Instead of trying to solve his problems for him, ask him what he plans to do and how he's going to fund it.
As a side bar, my daughter eventually got clean and did so without the benefit of a managed detox or rehab. Unlike her stints in rehab, she took ownership of her own recovery and future.