On fundamental decisions

In case there's any doubt, the headline "Iacobucci to decide" is absolutely meaningless until we know what the former Supreme Court justice is actually being asked to review. And there's plenty of reason to think that the Cons' appointment is aimed at everything but the core issue of parliamentary supremacy:

“Members will understand that there are matters must keep confidential in order to keep the public interest,” Mr. Nicholson said Friday in the House of Commons. “At the same time recognizing the legitimate interest that we all have in the protection of the men and women who serve us in Afghanistan and who serve the public interest in this country.”

Nonetheless, said Mr. Nicholson, “the government acknowledges that it is appropriate that the decision made by officials on the disclosure of information in these circumstances be reviewed independently from government.”

So from Nicholson's statement alone, we can conclude the Cons:
(a) are seeking to have taken as a given that they're entitled to suppress information even in the face of an order from Parliament; and
(b) are pointing Iacobucci toward decisions of "officials" (presumably earlier in the process) rather than the personal obligations of Peter MacKay in the face of the order passed by the House of Commons.

Of course, the Cons shouldn't be delaying even if the scope of Iacobucci's review actually does cover what should be a clear case of parliamentary supremacy. But there's particular reason for suspicion based on how Nicholson has framed the appointment.

Edit: fixed label.