I think you are being too harsh on the author. While it's true that deer and moose are commonly found in the same areas today, on an evolutionary timescale this is a fairly recent phenomenon. Being taller, moose can handle significantly deeper snow than deer without foundering. And when it comes to really extreme cold, they are indeed better insulated.
In the part of Vermont where I am, we don't get cold enough to faze the deer, but sometimes the snow gets too deep for them. Right now we have about a foot on the ground, and I saw tracks from both while out skiing today. But once the snow gets to 2 ft or more, the (surviving) deer will move to somewhere lower elevation but the moose can usually remain for the rest of the winter.
> Canada (the entirety of which is north and colder/snowier than MN)
Umm, no. Most coastal Canadian areas are much warmer in winter than Minnesota, and Hamilton ON is farther south than the bottom of Minnesota. As a trivia fact, did you know the southernmost part of Canada is actually south of the California/Oregon border? https://proudgeek.wordpress.com/2009/03/04/strange-maps-cana...
Anyway, I think the article isn't actually that bad, and while the author might have oversimplified, I don't think she's making things up. In her defense, here's an earlier piece that talks more about the moose/deer traditional habitats:
So why have moose never developed a tolerance for brainworm, as have deer? The answer lies in the fact that moose and deer haven’t shared the same habitat for very long, in evolutionary terms.
The Latin name for white-tailed deer is Odocoileus virginianus, or Virginia deer. It is exclusively an American species that first appeared in the southernmost part of North America some four million years ago. As recently as 15,000 years ago, whitetails were confined to the southern end of their present range by the continental ice sheet and didn’t return to northern areas until the glaciers receded.
Moose by contrast are a sub-arctic and boreal species with their origins in Asia. They are a relatively recent immigrant to North America, arriving during the same ice age, when a land bridge opened between Siberia and Alaska. Moose crossed east just before the time that deer started returning north.
https://northernwoodlands.org/outside_story/article/moose-su....
And here's one of the scientific papers on which the popular articles are based:
ABSTRACT: Declines in moose (Alces alces) populations have occurred repeatedly during the past century on the southern fringe of moose range in central and eastern North America, generally in the same geo-climatic regions. These prolonged declines, occurring over a number of years, are associated with higher than usual numbers of co-habiting white-tailed deer (Odocoileus virginianus).
https://wolfwatcher.org/wp-content/uploads/2017/12/2010_Lank...
> White-tailed deer and North American moose don’t normally share habitat; the deer’s shorter legs and thinner fur aren’t suited for the deep snow and subzero temperatures that moose prefer.
White tail deer range well into Canada (the entirety of which is north and colder/snowier than MN) and always have, from what I can tell.
It's like the person who collected the facts wasn't the one who wrote the article, and the author decided to fill in some gaps by just making stuff up that supported their thesis.