Sorry to hear about this. Not to be overly technical, but these are grizzlies and not brown bears. There's a difference.
Also, this was an archery hunt, so there was no gunshot to associate with a free meal. Evidently, from the report that I read, the hunter shot the elk one evening and they didn't recover it until the next day so it laid around in the woods for a period of time. It also said there was more than one bear involved so it was possibly a sow with cub. Kind of a perfect storm for something to happen.
When I was a guide in Montana, we were not permitted to carry a firearm of any kind while guiding. If that was the case here as well, and all they had was a bow, it was definitely a bad situation.
This is just one more reason why that federal judge needs to get out of the way of the proposed grizzly hunts in those states. Griz are amazing animals, but until they are hunted a little and learn to have a fear of humans, they will continue to be emboldened and situations like this will occur. It's sad for everyone involved, even the bear, which will likely be hunted down and euthanized if they can find it. Definitely sad for the guide and the hunter. Prayers go out to them and their families.