Need advice and also a warning.

The guy is a tool . all suggustions are cool but I would add : plaster his name and business all over social media and keep doing it . If you don't lie in the media he has no grounds for liable . Or, sue him for $10,000 liable and damages and let the court sort it out . I'm sorry that you live in the "Peoples Republic of California". We have other ways of dealing with asshats around here .