So I actually work in the ER in the US, and there are limitations on what you can and cannot do when someone who is refusing treatment. (which I almost guarantee he is)
There's a very specific criteria someone has to check off in order to get the help that they need if they are refusing care.
If he's acting just sane enough, he can refuse healthcare and there's nothing that police or healthcare professionals can do for him.
It's unfortunate, but that's where our healthcare system is at currently.
On top of this, mental health is such a tricky thing to evaluate because while someone may be showing signs of getting better, people in these types of states can pretend to get better in order to get out of whatever treatment facility they may be in.
There's only so much you can do to intervene because you also have to make sure you're not taking anyone's rights away.
Edited for punctuation purposes