I don't think the government actually wanted to stop math [1] from leaving the border. It was just a tool to use against people they suspected being involved espionage. Just another reason to put you in a cell.
Thomas Sowell wrote a quite a few good books about this.
I have no doubt it applies equally to export laws.
The wiki link you provided does not have the words "export" or "espionage". Are you trying to imply that R,S, and A were suspected of espionage? You'll need a real source for that..