Legal action by the protesters is exactly the correct response because the court has no option but to rule in their favor. If the court ruled against them then it would set a legal precedent allowing protestors to likewise spray paint people without legal consequences. Either spray painting people is legal, or its not legal. The court can’t have it both ways. If it is legal for the contractors…then it is equally legal for protesters. Obviously, the court doesn’t want to legalize that because there are potential health risks and financial damage to property (glasses, clothing, jewelry, etc.) when people are painted.
Additionally, depending on the type of paint, using the paint in a way not approved on the label may also be a federal crime. This is why it is illegal to use “Bear Spray” or “Wasp Spray” against humans.