You never get legal threats thrown at you for agreeing with 'guru's', only when you say something against them. If I recall correctly Henry Kaye's organization was pretty good at it as well, until he was closed down by the authorities.
Yes, we never hid behind the fact that there were legal threats. In my understanding of Australian law, a company (or an individual) has the right to defend themselves against untrue, unfounded, or outright malicious remarks which might materially affect their reputation and ability to reasonably earn an income or might prejudice them unfairly.
Just FYI - we don't automatically delete posts just because we get a threat. There was a case recently where we got an email from a representative of a company who complained (and threatened legal action) about a thread which negatively discussed their company. After reviewing the thread, Ian and I agreed that the post in question was quite legitimate - it explained one person's experience of dealing with a particular company and made no accusations of impropriety or illegal activities or anything else like that. It simply said what had happened (from their point of view) and expressed their dissatisfaction about the outcome.
We told the company representative that they have a right of reply and that we wouldn't be removing it.
However, we did remove some subsequent posts in that thread which did make accusations (without evidence or explanation) of wrong-doing or was misleading in its content to the point where someone reading the thread could possibly get the wrong idea about the company's involvement in some activity.
There was another case where someone linked to articles about a company on a newspaper website and on a Dept of Fair Trading website, describing some court action taken against that company. A representative of that company complained and threatened legal action, but we responded saying that they were merely reporting the news, which we thought was reasonable. As it turned out, the news was actually inaccurate and misleading, and the newspaper and Dept of Fair Trading were both forced to remove the articles from their websites - at which point we agreed that it was reasonable to remove the thread in question, since it was also misleading.
It's never a black-and-white thing. A number of times I've had to instruct moderators not to automatically remove posts which are negative - it really depends on the context and content of the post.
With the situations we're referring to, a post of something like "I invested in product X, and over time period Y, it only showed Z% return, contrary to that promised by the guru", would have been fine. Even a post of "comparing the performance of index X to the performance of this fund over time period Y, you would see that it underperformed by X%", would be acceptable. Indeed, I believe there were several of these made at the time.
What is not acceptable is continuing to post over and over again in a combative manner, "crusading" against a "guru" you've taken a dislike to. This is where opinion starts to become malice - something you will get into trouble in court over. Many of the posts made at that time could easily be taken out of context and made claims that were unsubstantiated (eg: "the fund can never outperform the index", or "you will never make any money out of this fund", etc). To me, that is clearly libellous and the companies in question (there were more than one I recall) had every right to complain, especially when such negative posts were made at just about every opportunity.
If you would like to read some information about defences to an action of defamation, here is a useful summary:
http://www.lawhandbook.sa.gov.au/ch14s06.php (click through the next few pages on that site to see examples).