As far as I can tell from the internet, to call an action a fraud requires that it has three elements.

• a false statement or misrepresentation of a material fact
• intent to deceive
• damages as a result of the deception

The first one is easy peasy, as there are plenty of records of falsehoods that were later edited out of existence, most notably the magnitude of the price support behind XPY. You can also add merchant support, etc. as things that were misrepresented.

The second is a little trickier. They can attribute a good number of the false statements to internal communication errors. The trick here is to get access to their internal communication. I'm guessing that those message board posts the CEO made prior to all of this, while not absolutely conclusive, might be enough to get a warrant for internal emails and private online messages.

The third one is trickier than it sounds. The most brilliant move they made was to convert those hashpoints to paycoins and let people sell them on the market. That reduced the number of potential claims, as most people who wanted out at that point sold their coins, at a profit, to those who wanted to stay in. This is in line with a lot of the private messages that have been posted on the board. The CEO didn't want customers who asked questions or otherwise didn't agree to follow him blindly. He banned liberally anyone who wasn't on board. That way all of the liability lands in the hands of a few true believers who are likely to blame external forces (dumpers, regulatory agencies, etc.) for their losses instead of GAW. They can probably handle a couple of malcontents with decent settlements. The people who didn't buy in completely pretty much all made money or broke even.