Dear Sitka deer,
You are correct. You actually have had some of the very large Canadian wood bison in Alaska ever since November of 2003, and some have been born in the state, but they are held where wolves likely cannot get at them even if they wanted to.
But you do have the smaller plains buffalo living in places where wolves can kill them.
I have read that Alaskan wolves do not tackle the adult plains buffalo so it only stands to reason they would avoid wood buffalo which are on average 200 pounds heavier as well as being much taller than a plains buffalo.
Size matters to predators.
Wolves in the high arctic are smaller than their moose-eating woodland counterparts just as high arctic grizzlies are smaller than their salmon eating Kodiak Island counterparts.
So Bergman's law isn't really a law as it does not mork in many cases. Its important not to take people with PHds, like Bergman, too seriously. They tend to be bureaucrats with stolid minds rather than intellectuals.
They gave us global warming which is an interglacial, they gave us the Canadian red wolf which is a feral dog, and they gave us the eastern panther which has never even existed.
There are only two kinds of cougars and the Darien Gap in Panama seems to be the dividing line between the two species.
A bit of skepticism is always a good idea because nowadays junk science is more common than real science. Charles Darwin didn't have a PHd.
