I'm more a Nozick style libertarian than a Rothbardian. You are correct about Rothbard, but I believe that his recipe for "competing adjudication agencies" is simply a recipe for disaster.
I believe that a single judiciary is necessary, it should just have the absolute minimum amount of power necessary to do its job, and no power to create new laws or positive rights.
I agree with you about needing a final judiciary.
Just wanted to point out that not all libertarians agree with us minarchists.