That's true, in the sense that in terms of the obligation they have, the SIRC counsel have a sort of bifurcated obligation. Certainly they are there to serve as the arm, if you will, of the committee member in question; yet they also, in the course of serving that role, serve the best interest of the person who's been excluded from these in camera, ex parte proceedings.
I don't understand why that bifurcated rule makes SIRC counsel less prone to make a slip-up in their questioning than an independent counsel would be in a security certificate context. They would be amenable to the same sorts of penalities; they would be under the same obligations not to disclose secret information. I see nothing in that institutional structure that makes SIRC more amenable to continued access than a properly structured special advocate system would be.