According to whom? The woman who was arrested? Is that what the arresting officers put in their report? Even if the off duty officer overreacted, the other two officers would also have to be negligent in their duties.
If she had been harassing them, and then said she would be quiet and just wanted to watch them, they have every reason to demand that she leave the area, because they don't want to come back if she starts harassing them again. The workers had every legal right to be there. The woman also has every legal right to be there as long as she respects the right of others and doesn't harass them.
And yes this happens often. The intimidation of land owners to empower the officer's second employer.
And what exactly are you basing that assumption upon?