And where in the OP does he state grizzlies killed on an expensive guided hunt?

There are way more bears killed as incidentals when moose, caribou, or sheep hunting by residents each year than guided hunters kill. Scores more killed with whatever is handy in the boat or snow machine by rural dwellers. A huge percentage of the time the rifle employed will not be some giant magnum.

And in AK there are no caliber restrictions.