Health Canada's guidance is to follow FAO/WHO guidance and prepare powdered infant formula with water that has been boiled and then cooled to 70C. They state this is because of concern with possible contamination of powdered infant formula during manufacturing from harmful bacteria such as Cronobacter or Salmonella. https://www.canada.ca/en/health-canada/services/canada-food-guide/resources/infant-feeding/recommendations-preparation-handling-powdered-infant-formula-infant-feeding.html
We haven't had any recent reports of Chronobacter or Salmonella contamination in Canada, but I note there was an outbreak of salmonella within the last year, with over 3 dozen cases in infants in France, Belgium, Italy and Greece, and a widespread recall by French formula maker Lactalis that impacted products in many countries around the world.
In ordinary household circumstances, Health Canada does acknowledge that cooled, previously boiled water can be used if the formula is consumed immediately and if any leftovers are discarded.
Of course, an emergency situation is not a normal household circumstance.
Our direct experience in the field in Canada during the mass evacuation of 88,000 people including 3,000 infants under the age of 24 months after the Fort McMurray/House River wildfire was that the main evacuation centre (serving 19,000+ people) experienced a gastro outbreak. During this time families were given tins of powdered formula which were opened and then used over the next several hours/days to prepare bottles without facilities that would allow for Health Canada's preparation guidelines to be followed. Save the Children workers touring the facility also reported a significant volume of opened powdered infant formula on the site during this outbreak.
The risk of contamination of open tins of powdered formula is a real risk in an emergency setting in Canada, and ensuring that emergency centres have facilities set up to allow WHO guidelines to be followed when infant formula is being prepared will reduce risk of illness for these infants.