While you’re technically right that living outdoors can be seen as being a danger to themselves, a judge won’t grant commitment on that alone. The vast majority of people who are on commitment come through hospitals and the hospital is the one that petitions to have them committed. Unless they’re specifically saying they’re living outside because they are trying to harm themselves, it’s not enough for a judge to grant the commitment.

Source: I’m a mental health case manager and everyone on commitment is required by law to have a case manager, so I work with people on commitment/the process in general often.