I have heard of gay people seeking reparative therapy voluntarily. Usually it's because of the standards of their peers, which they have internalised, so the extent to which they are an "unwilling recipient" probably depends on whether you include subconsciously unwilling.

Anyway, I don't think you should stop people doing stuff that's bad for them, if they really want to do it and are fully informed that it's bad for them. I also fully support and applaud professional psychology bodies kicking out people who provide this sort of "therapy" though. Their "services" should come with a health warning, like cigarettes. "Warning, this therapy doesn't work and will probably damage your mental health", that sort of thing.