A Waste of Taxpayer Money.
The protesters will be released, no charges filed. They didn't break any laws and no DA is going to bring charges. Resources (tax payer money) wasted in this fruitless exercise. But the HO has an excellent basis for filing a lawsuit. WELL, as far as the police TRESPASSING, State laws give law enforcement officers exemptions from certain criminal laws if it is necessary to violate them in the process of doing their jobs. Would love to see this case go before a court, challenge the exemption here. If the protesters hadn't broken any laws, were invited on to private property, there was no legal excuse for the police to trespass. They were not carrying out a legitimate duty. 
This wasn't a simple mistake, however. Most police know the law. They violate it all the time because when that happens, it is hardly challenged by anyone except by the victim in a civil court. If the victim wins their case....HO HUM. The tax payer foots the bill, the police department is off the hook, hardly ever held responsible for reigning in police officers who knowingly violate laws.