I am surprised it's been quiet too. Though I'm not sure we can conclude that a foreign national would not be held accountable for insider trading of US stocks. Here is an interesting article. It may be a little dated (2013) and I'm no expert.
A recent inquiry into potential insider trading in Switzerland ahead of the acquisition of H.J. Heinz Company has drawn attention to the role of U.S. regulators in policing suspicious trading activities that take place outside of the United States. While the Heinz matter has attracted significant media attention, it is only the latest in a string of similar cross-border inquiries and enforcement actions undertaken recently by the U.S. Securities and Exchange Commission (SEC). As these matters demonstrate, the SEC has in recent years shown an increasing willingness to pursue insider trading enforcement actions with substantial international dimensions. In the words of former SEC Enforcement Chief Robert Khuzami, “offshore trading is not off-limits to U.S. law enforcement.”