Doctors seeking to gag their patients

Doctors are asking patients to sign waivers agreeing not to post comments about their services to online rating sites such as Angie's List and Kudzu.com, on pain of refusal of treatment. See story here. I find this reprehensible, and any doctor who made this request of me would be dumped so fast her head would spin like Linda Blair's in The Exorcist. What say you?