Mental health problems by any chance? He may need more help than family can provide if you want him to get back on his feet (and out the door).
It would be a good sign if he seems like he wants to get his own place again, even if he’s not able to make steps towards it.
Source: I’d probably be in the same boat if the laws and property upkeep rules were stricter here. Even so, I’d be wanting to get out of family accommodation ASAP. My family are good people, but I can’t spend long periods with them. There might be a hint or two in that somewhere.
(But whatever you do, please don’t fail to be kind.)
Rest assured that they’ve already had that idea a dozen times already, and if they thought they could make it stick, they would have done so by now.