Wild One - I grew up in Alpine and Highland UT, so am familiar with the area also. I do not accept that just because you or a few other folks that spent some time in the area did not see any bears that there have been no bear sightings in the area. I live in Montana now where there are quite a few bears, both black and grizzlies, and I know several folks here that have not seen bears in the wild either, though they are not too hard to find if you're looking for them. Generally, they want to stay away from people unless they've been fed.
Also, just because an area is not part of a national park or monument doesn't make it fish and game jurisdiction. I would expect this area to fall under the forest service, not fish and game jurisdiction.
If the forest service, fish and game or other agency were required to shut down areas whenever there was a risk of bear, mountain lion, moose, falling tree or whatever, they may as well close the forests and people should stay at home. There are many lawsuits from various states and in the federal courts on related issues of what warnings need to be given and when, and frankly, these types of suits mostly unsuccessful for plaintiffs, end up putting barriers, fences, signs, etc. all over the place that, to me, destroy the wildness of the outdoors.
Again, there are bear warning signs in that area of the canyon warning of black bear. Your post suggests you, like others, simply ignore them because you haven't seen the bears. This tragedy is unfortunate, but so is the blame thrown around because of it.