Yes, maybe so.
I believe that before there is a challenge, there must be internal processes within the public service to ensure that the exception is not invoked excessively. Since the public service is under the control of Parliament, you may have a role to play in this regard.
I don't think it's easy for a committee like yours to review on a case-by-case basis all the public tenders that the government submits in a year. Your role would probably be to ensure that the government is putting in place procedures so that the national security exception is invoked for more specific contract categories, and also to clarify what aspects of the applicable rules should be excluded from the Agreement on Internal Trade, for example. You might say that this or that rule won't apply, and not just say there will be no more control or rules. That is the meaning of the general exemption currently being invoked.