My understanding is that the recent thread in question was closed because it had become argumentative and because it had devolved into a discussion between a few people that had little to do with the original poster's question (ie it was hijacked).

I do think that they too often close threads where debate becomes spirited. I have a pretty high threshold for spirited debate and generally think it's appropriate as long as it remains respectful. However I think the forum's moderators are somewhat more reluctant to let significant dissent unfold. I suppose that is their prerogative.

I have not found that certain viewpoints are censored more often. There's lots of skepticism about psychotherapy and medication on the forum. I think it's really the tone of the debate that shuts down threads.