Should be a fascinating case to read, but I've only had time to skim. I've been waiting for this opinion for some time now and have been discussing it at CLE's in the context of a continuing duty of loyalty after the attorney client relationship (ACR) ends.
A real estate lawyer helped a client with a proposed project, the ACR ended, and then the lawyer got involved in some public speech and community lobbying against the project, all without revealing client confidences. The client sued and the lawyer successfully invoked an anti-SLAPP defense. The California Supreme Court says the suit may proceed.