[frobozz]

In broad terms, I agree, and in many cases it is a societal problem. However,

FTA: >He wasn't a danger to himself or to others, he wasn't threatening anyone, he just didn't look very respectable.

This is the missing condition required to withdraw a patient's liberty in a secure hospital. Even if he presents with severe enough problems to become a voluntary inpatient, he may still wander off and be difficult to find. Due to the nature of this kind of illness, you are likely to cease seeking care when your problems become that severe, and need someone else to push you into it.

Although he had medication that he wasn't taking, it sounds like he was living on his own when his problems became that severe, so he probably had no one to push him to the doctor.

All that said, there should be people looking out for the homeless and making sure they get the medical treatment they need, and maybe the definition of "danger to self" needs looking at, as choosing to sleep rough during a hurricane sounds pretty dangerous to me.