I think I'll disagree on that one.
I see s.1 more broadly than that. Don't forget that there are numerous western countries with constitutions as strong as ours which have had conscription as part of their heritage.
In the US, the constitution's authority given to Congress to raise armies was held to permit it to do so through conscription. The USSC upheld that. Canada's constitution at s 91 7 gives that authority to the Federal government
The
EU has also left the issue to individual countries when it dealt with the issue of limiting compulsory military service to men only.
There is a general reluctance of courts to interfere in the rights of the legislature and executive in general in matters of national security.
Restricting conscription to "periods of extreme literal national survival" is impractical because again it would fetter the executive from deciding when that national survival is at risk. That is a political and not a legal question. Just as an aside remember that not only did the National Resources Mobilization Act of 1940 authorize military conscription but also to register workers and move them into defence related industries.
Similarly the current Emergencies Act has a provision for an "International Emergency ... that arises from acts of intimidation or coercion or the real or imminent use of serious force or violence and that is so serious as to be a national emergency." and which includes provisions to "the authorization of or direction to any person, or any person of a class of persons, to render essential services of a type that that person, or a person of that class, is competent to provide and the provision of reasonable compensation in respect of services so rendered;"
There is, under that Act also a "War Emergency ... means war or other armed conflict, real or imminent, involving Canada or any of its allies that is so serious as to be a national emergency" which provides broad regulatory powers BUT "(2) The power under subsection (1) to make orders and regulations may not be exercised for the purpose of requiring persons to serve in the Canadian Forces."
Accordingly, while the Emergencies Act can provide for major defence industries and workers in that regard, it cannot, by itself, create conscription. That requires a separate Act of Parliament such as was done in WW1 and WW2.
The final bullet in the issue is s 33 - the "Notwithstanding Clause". I sincerely doubt that the present government would ever use it in this type of circumstance but I would expect in the right type of situation, some government will. IMHO, if the situation is dire enough to require conscription, either during war or under the threat of war, then a government would use s 33 either immediately or if challenged.