Sorry I'm late joining this thread. I've been having some problems getting into the Forum the last two days.
Subject to my usual "I'm a few years retired now" caveat -- here goes.
There are several legal provisions under which CF personnel might be used in these (somewhat vague) circumstances.
1. Aid of the Civil Power is a situation where a provincial civil authority is faced with a riot or disturbance of the peace which is beyond its powers to suppress, prevent or deal with. In such a circumstance the provincial attorney general issues a requisition under Part VII of the NDA in a prescribed form directly to the CDS
(no federal minister is required to be consulted although in practice they usually are). The CDS must respond
by calling out such part of the CF as he considers necessary to suppress or prevent the riot or disturbance. CF personnel at all times remain under military command and remain called out until the civil authority concludes that CF assistance is no longer required.
2. Under s 273.6 of the NDA, the GiC or the MND (on the request of the Solicitor General or any other minister) may authorize the CF to perform any duty involving public service that is military in nature and that is in the national interest and that cannot be effectively dealt with without CF assistance. Note the difference from ACP is that the provision is broader that riot and disturbance and can be initiated at the federal level without a provincial attorney general requisition. This provision has been and is being used for a variety of situations such as assistance to fisheries enforcement, assistance to federal penitentiaries, CF Armed assistance to the RCMP (CFAADs), CF assistance to provincial police forces (CFAPPFDs) and various MOUs such as assistance to RCMP re drug ops, surface ships and aerial surveillance re fisheries, environmental emergencies response.
3. Emergencies Act The Act is very broad in nature and includes various types of emergencies including "public order" ones. Emergencies must be ones which are urgent, critical ones of a temporary nature that seriously threaten the public safety, health or lives of Canadians and are of such scope as to be beyond provincial capacity or are ones which threaten Canadian sovereignty, security or territorial integrity. It generally would not apply in situations such as lawful dissent or protest. The Act is triggered by a GiC declaration.
The various provisions above are complex and nuanced and I'd be hard pressed to describe what is being contemplated in the article although I think I can reasonable say that it wouldn't be the Emergencies Act. Which of the other two remedies are being contemplated would really depend very much on the circumstances and the provincial/federal agencies involved/effected.