Apologies to anyone who isn't a law nerd for the following.
The Judge in this case found the Forest Service negligent, meaning Forest Service employees breached some duty they owed to the Plaintiffs. So what is that duty? Is it the duty that everyone owes to everyone else to use reasonable care? If that were the case, it would mean that you, another hiker who just happened to hear of the earlier bear activity, had a duty to inform the authorities about it. While I think, in that case, you certainly should inform them, I don't think the duty extends far enough that you could or should be held liable to the tune of $2 million if you don't.
The next option for the source of the duty is arising as part of Forest Service employees' duties arising by virtue of them being employees. If it is the Forest Service's job to keep recreational outdoors users safe from the outdoors, then there would be such a duty. But I think the Forest Service's job is more to protect outdoor resources from people.
The final source of the duty, and the one on which I think the Court probably settled, is the regulations that one Forest Service employee breached by failing to notify her superiors of the prior bear activity on her day off. That makes this a negligence per se case. To state a case for negligence per se, the Plaintffs would have had to show that they fall within the class of people the regulations are intended to protect. If the regulations requiring a response to reports of bear activity are intended to protect outdoor recreationalists, I can see why the Court ruled the way it did. And maybe that really is the intent of the regulations. On the other hand, maybe the regulations are intended to prevent harmful wildlife vs. person encounters for the purpose of protecting the wildlife. If this is the case, and I think there is at least a plausible argument that it is, the Plaintiffs' can't assert a negligence per se claim (though maybe the bear could have, supposing it were a person and could have standing).
Having said that, I'll add the caveat that, while I have read the decision in this case, I have not read the cases cited within it, or the regulations or their history.