The unregulated stock market was illegal.  If a group of individuals wanted to sell out shares in their illegal business because one brave man was about to go to the federal regulators, that sounds like a scam to me. 

It's not like this is the first time Theymos has been involved in extremely shady business either.  He admitted profiting off the Pirate ponzi IIRC and felt he did nothing morally wrong in the process.