after proceedings had started, wasting everyone’s time and taxpayer dollars.

That was the point - that is, that’s why the cop didn’t just walk away. He knew he was wrong, but she embarrassed him. He knew that he could just force the issue right up to the last minute, and there would be no consequences for him. Major hassle and inconvenience for her, but he still gets paid and there’s almost certainly no negative repercussions for him.

He was deliberately making life more difficult for her, because his feelings were hurt. It wasn’t out of ignorance, it was out of childish malice.

The article mentions felony charges - it could also or instead be that it was too high a bar (pun intended) to indict when it should have been a misdemeanor vandalism charge.