As I understand it the SEC has begun to classify crypto-coins as an official asset class based on various criteria[0]. This means that while bitcoin and other alt-coins may not be a "Stock" they are being considered a "Security" under U.S. regulation and thus saying Big Vern commited securities fraud is not inconsistent with U.S. regulation.

[0]: http://www.businessinsider.com/bitcoin-price-security-equity...