Aren't libertarians supposed to consider liberty (whatever that means) as the highest political aim? According to this definition, you can't get more libertarian that Roberts since he put his personal life at risk in order to increase the liberty of a few like minded cohorts.

I support neither drugs, libertarianism nor the Silk Road, but I don't like to see people judging who can or can't be a libertarian based on their own moral preconceptions. The only thing that matters in the definition is how much the individual in question has furthered the goal of more liberty.