Leftists at The League of Ordinary Gentlemen, like Elias Isquith, promote a deliberate misunderstanding of libertarianism because, I guess, it threatens their statist worldview. The typical strategy to marginalize libertarianism is to associate it with "hard rightwing" ideology. In the article linked to above, Isquith relies on Tim Carney, who likely misunderstands libertarianism out of ignorance. I know that at the League the subject of libertarianism has been discussed enough times that only someone determined to misunderstand it would write what Isquith wrote.
What Isquith and Carney are getting to is that libertarianism is like social conservatism, and that social conservatism and fiscal conservatism go hand in hand. Carney assumes that most libertarians think Jim DeMint is a libertarian. Because one Reason writer says that DeMint was a friend to libertarians in the Senate, somehow Carney and Isquith use this thin piece of evidence to make their case. Like most people who misunderstand libertariansim, whether purposefully or not, they miss one vital part of libertarianism in making their case. They show how DeMint holds social conservative values, yet he doesn't necessarily want government to enforce his values. Non-coercion is a libertarian principle, unless coercion is used by a limited government or private security organization to protect people from coercion. But adhering to a principle that is a libertarian principle doesn't necessarily make one a libertarian. It could, and DeMint would have to decide if he thinks he's a libertarian thinker -- I don't think he is, but then I don't know how deeply he adheres to the non-coercion principle.
I'm not even sure that calling a person a libertarian and putting them in a group called libertarians is actually correct. As Isquith points out in the comments section, those on the Left who claim some libertarian values are acutally modern liberals or progressives or whatever -- it depends on how the individuals, and those who critique his/her political thought, characterize and label their political views. Labels are useful but most thinkers will agree that strict adherence to labels is too restrictive for most of them, especially libertarianism which actually grew out of liberalism as liberals in the early 20th century split between libertarians and modern liberals.
I don't mind anyone calling me a libertarian, but all it means is that I adhere to what are known as libertarian principles. I would also be fine if someone called me a classical liberal. When discussing libertarianism as Isquith and Carney are discussing it, only a few things matter -- does a person promote a limited government that protects basic rights, does a person adhere to non-interventionism in foreign affairs and does the person believe in economic liberty? I don't care if DeMint opposes abortion or gay marriage as long as he doesn't promote government enforcement of these values on the public. If DeMint is consistent with the non-coercion principle, then he would also be against the War on Drugs. I don't know where he stands on that. Again, though, this doesn't mean that a libertarian thinking person condones drug use, it's just that the person would not want government to interfere in peaceful behavior that doesn't violate the rights of others. I'm not sure that given the vote, if a real opportunity presented itself, though, that DeMint wouldn't vote to use corcion to advance an opposition to gay marriage, abortion and drug prohibition, just to name a few social conservative positions.
But to spin and flip the issue to associate social conservatives and fiscal conservatives, then to show a friendliness between libertarians and conservatives, then to make the giant leap to equate libertarianism with social conservativism, is either ignorant or an attempt to marginalize libertariansim.