It is more of a legal argument than a moral one. If a person is driving dangerously should they not be cited if it is determined that they are not legally intoxicated? Why not instead bust people for driving dangerously and only allow for intoxication to be an enhancement. The law is HIGHLY technical, and Rockwell likes to often attack it in highly technical and extreme ways. His articles tend to be worth controversial discussion and not group think.
Ayn Rand is not the beginning or end of libertarian thought. She was a contributor. She also supported the idea of using war to promote US interests, possible the most anti-libertarian position anyone could take. Just because something has a founding in Libertarian principles does not mean that the conclusions that individual comes to is representative of all Libertarians.