In terms of a solution or way of dealing with this issue, I think the Canadian International Trade Tribunal Act does not at all cover the national security exception.
If a mechanism is needed to address the issue, the act may need to be amended and set out that the government may, under certain conditions, invoke a national security exception by providing certain information on the scope of the exception invoked and its justifications. Then, the tribunal would decide whether or not the exception was justified. When you get right down to it, the process isn't very different.