That is the part I do not understand. I have never agreed with any health professionals to be part of his ongoing care. I suspect his family may have done so, but are abandoning their responsibility?
He had agreed to let me visit him in hospital very shortly, before he is discharged. I intend to make it very clear to the staff that I have not agreed to have any official role in his ongoing help.
You're right, you're not his caregiver, or obliged to be. Sorry if it sounded like I was suggesting that.
I doubt the staff would expect or pressure you to take responsibility for him. If anything you might have trouble getting them to even discuss his case with you - different states vary but in some cases they won't share case details without explicit permission from the patient. (If that sounds frustrating given your first hand experience of his symptoms and their progression - I sympathise.)
The support groups in particular may be useful despite that, just because you mentioned he's a housemate, so he may continue to be in your life. When I attended there were spouses, parents, but also just friends who wanted to help out their friend and understand what they were going through, without adopting responsibility for them.
He had agreed to let me visit him in hospital very shortly, before he is discharged. I intend to make it very clear to the staff that I have not agreed to have any official role in his ongoing help.