Sorry to hear about your situation. I would agree with you that it sounds like he is in a depression, and that he needs help. I would ask friends and
relatives of his to help you convince him that he needs help. Perhaps a trip to his regular doctor, after you call his doctor to express your thoughts, might be helpful to get him started on an anti-depressant. That would be a good first step. Often, I find that convincing a patient to see a Psychiatrist right away is more difficult - comes with a stigma and the patient is resistant. However, if his regular doctor can get him started on an anti-depressant and then later convinces him to see a Psychiatrist, that may work out best. Of course, if he is having any suicidal thoughts, then you would need to seek the help of a Psychiatrist immediately.
Overall, depression works against the patient very much in the effort to improve after stroke. I agree with you that this issue needs to be aggressively addressed.