What are you supposed to do about people who haven't got anywhere else to go to the toilet?
If you place them in custody, you might as well provide them with some basic housing that costs less than jail. They have literally nothing to lose from fines, court dates, tickets, probation. They don't have a toilet, what else are you going to take away from them.
The police are correctly judging that the need to defecate is not a criminal problem.
The question was not 'what do you do if you need the toilet?' but 'what do you do about people who haven't got anywhere to go to the toilet?'
By definition, if there is a public toilet accessible to you, or you are welcome in a restaurant toilet without paying, you have somewhere to go to the toilet.
If you place them in custody, you might as well provide them with some basic housing that costs less than jail. They have literally nothing to lose from fines, court dates, tickets, probation. They don't have a toilet, what else are you going to take away from them.
The police are correctly judging that the need to defecate is not a criminal problem.