Similar story from my youngest brother - some years ago, he was RCMP stationed in Thompson, Manitoba - multiple times called out due to "problem" bear in town - would pull over and wait for DNR to show up - DNR would pass along a few 12 gauge slugs - experience had shown them that the RCMP issue buckshot was not nearly as effective as a slug, when in a tight spot. Is no doubt in my mind that some higher up RCMP "desk jockey" in Ottawa had decided that slugs penetrated too much for officers to be able to use - so was only buckshot available to them in the field - made it "safer" for bystanders, or whatever. However, that ignores the issue, in your face, that you want to STOP that thing right where it is - and that might not be the same as "killing" it.
When we drilled at the nickel mine in Thompson we kept a 12g with slugs in the sea can and in the drill. Always took it to check water lines, saw lots of wolves but never a bear.