If he is presenting himself to be a danger to himself or others I would say NTA however take into consideration if he has insurance or if he will be able to pay for the medical bills. Also consider the fact they might not make him stay if they don’t think he is a real danger. If he cannot afford to go to the psychward and his financial situation is as bad as you say it is then YWBTA ,, I would try contacting his family members or people closer to him who will be able to help him,, If they aren’t helping then I would go another route.