No I think the police could simply say they couldn’t stay where they were at because there are shelters available, of course not following an order to vacate could result in an arrest. BTW I make sure the homeless around here know that LA is very friendly to homeless. Weather is better too. 
In other words, they chose to arrest based on actual hazard posed to others (i.e. perhaps he was worth the jail space/cost more so than any homeless people who are merely unsightly).
Those who don’t live in California perhaps don’t understand what comes with people living on the streets.
They block sidewalks with trash, needles and human
waste so that it is unsafe to walk. And forget about using public parks or bike paths. A neighbor recently needed to change her baby in a library restroom and the baby accidentally touched foil containing drugs and had to be rushed to the ER.
Untreated sewage is in the streets and goes untreated to the ocean.
Theft is increasing from stores, cars and homes.
Those crazed out on drugs attack people verbally and throw things and hit motorists.
Downtown there are so many rats in the garbage that typhus is spreading. Police have contracted typhoid fever in areas with large encampments.
And we are just one windy day away from another wildfire from illegal campfires.
This is the number 1 issue in my area . People are angry at the city and state so called leaders.
Unsightly is not the issue.
^ That’s why people move to Marin, where they can bask in the glow of their virtuous concern for the downtrodden in style and comfort!
The problems is drugs. Like the man in the OP’s original story. He was educated, had a good job, had a home and then started using meth and lost it all. He could move in with his father or live in a shelter which someone who is just without a home would do. The people on the street are (in the main) drug addicts. Drugs are a scourge and a more severe crackdown on their use and distribution is needed.
I would say that mental illness is probably more of an issue than drug addiction. Many mentally ill people use drugs to self-medicate.
This was the case for my client that provided mental health services for a major metro area. At one point they calculated that there was a 75 - 80% overlap, meaning of their SMI clients, 75 - 80% also had substance abuse issues.
Follow up article shows that networking at this elite pays off. Contacts made are invaluable.
https://www.cnn.com/2019/11/08/us/homeless-yale-grad/index.html
That’s true for even non elite schools. A lot of big publics have great networking systems that pay off big for alums.
I hope Mr. Pleasants can overcome his addiction problems. I don’t see how he can achieve his goals without doing that. But he does seem to have an inner strength. I’m crossing my fingers for him.