Since Hyman joined the Oilers he's 5th among Canadian players in goals with 125. Only McDavid (154), Point (145), Reinhart (140), and MacKinnon (138) have more. He's also first among Canadians for playoff goals in that time with 30. So yes his larger body of work is very impressive and Canada left him off the team due to a cold month.
Its a short tournament where chemistry among players will be very important. And Canada decided that its best player didn't need one of his most regular linemates, one who happens to be one of Canada's top goal scorers.
Its a weird decision.