Well, I don't want to comment on the government's practices. I prefer to talk about the House, the committees and their powers. In my opinion, the important thing to bear in mind is that committees and the House play the role of the “grand inquest of the nation”. This is a constitutional power recognized by the Supreme Court. It is fundamental. It was also recognized by Speaker Milliken in the ruling I quoted.
That is why statutory exceptions do not limit the committee. It is up to the committee to make that decision. However, as Speaker Milliken himself said in his ruling, some public interest imperatives really should not be minimized, but it is up to the committee to make that decision