Tom Claycomb is an industry writer. It was likely an assignment to use the Mossberg. If you can afford a full price Brown bear hunt, you aren't hunting with a bargain basement rifle, no matter if you treat it worse than Spomer does a hammer.
You can like your 300WM Patriot, but don't be so defensive. How is a Patriot different than the Mossberg 4x4? Weren't there stories about 4x4s blowing apart? When the Patriot came out, I never read if it was a different action than the 4x4. Regardless, the 4x4 problems must have been fixed because the Patriot has had much better reviews. I think Boddington has hunted with one, but that was an assignment.
Again, on a trip like that, you buy the best gear you can afford. A $400 dangerous game rifle isn't it.