Shit man, I call myself a Libertarian and I think all drugs are evil. Just because you think someone should be allowed to do something doesn't mean you believe that it's good if they actually do it. It's perfectly consistent to think people should be allowed to say whatever they want, and that they should also be ignored the moment they do so.
Discussion
This is way too difficult for most people to understand. Somehow
Not really. Most of the time it's just irrelevant. Most of the time Libertarianism isn't relevant. Libertarianism can't make you a good and responsible human being. All it can do is prevent you from being evil. Plenty of Libertarians are ethically neutral pathetic moochers. A Libertarian philosophy isn't enough to explain those losers.