I understand the argument you're trying to make, but the problem is that "liberty" is not a term with a universally agreed-upon definition on which you could base uncontroversial assertions that something is "likely to lead to more liberty," or even that a particular state of affairs involves more liberty. This word is first and foremost a strong applause light, not a precisely defined term that would enable us to consider any hypothetical states of the world X and Y and make an uncontroversial and universally accepted claim that X means greater liberty than Y.
In this case, there is an ideological dispute in which both sides would claim to be in favor of more liberty, however the disagreement is not just about what policies are likely to lead to more liberty in practice, but also about the very definition of "liberty" that one is supposed to be striving for. And you can't support any side in this disagreement -- at least not casually and without a very careful justification -- without going way out into the mind-killing territory.
Ok, I better understand your objection now. I'm not sure that I see, however, why this objection wouldn't apply equally well to Eliezer and Michael Shermer (or anyone else) using the term "libertarian" to describe their views. (I take "libertarian" to mean "in favor of more liberty," more or less)
A response essay written by Eliezer Yudkowsky posted at Cato Unbound for the issue Brain, Belief, and Politics:
Is That Your True Rejection? by Eliezer Yudkowsky
The lead essay has been written by Michael Shermer:
Liberty and Science by Michael Shermer