This guy was a well known poster. I'm sure he thought he had some power to motivate wsb users to invest, but he might not have predicted he had enough power such that he would get embroiled in an investigation. Regardless of how "internet-tuff-guy" people are, most people really don't like to suddenly be thrown into the limelight of a financial fraud investigation, even if they are innocent of any crimes.
Thus, the CYA language. Better to get out in front and claim ignorance just in case.