The same argument again. The hypothesis is that a heavy for caliber bullet in 22 or 6mm will do the job in harvesting animal X. Lots of people argue other calibers are needed to do the job, yet few offer any examples of the original hypothesis either working or failing. You don’t disprove the original hypothesis by proving a big bore works, all that proves is other solutions exist to the problem at hand.
I have never hunted a bear, but do know they can be killed by an arrow. A coworker and his father both got deer by bow in Canada. That suggests you don’t need a magnum to get the job done.