Yes - that indicates the hyoid bone was broken. IME, one of the reasons strangulation is such a common form of DV (even if not unto death), is that the strangler wants to immediately silence the victim. The hyoid bone and its cartilage (breaking/ripping either is a sign of strangulation) are next to the voice box and the strangler grabs the neck with their thumbs just above the voicebox (larynx). Problem is, if they let go, the victim naturally starts screaming or yelling. This is not the most efficient method of strangling someone as MMA fans will point out, but the average person doesn't know how to efficiently strangle someone and there's no evidence that Brian was into MMA.
Boa constrictors are not native to Bridger-Teton NP, either. Bears do not strangle (or have opposable thumbs with which to do so). We don't know the full details of the report, but it's possible, even likely, that there was damage to the cervical vertebrae from the other fingers.
Biological anthropologists have written quite a few articles about adrenalin and hands (if people go into the "fight" mode of flight or fight, the adrenalin and the nerves in the hand and wrists are highly activated). In anger management and behavioral therapy for people who violently act out, learning to keep the hands relaxed and to step away (flight, not fight) are key ingredients. Many people in anger management classes say that their hands took on a life of their own and "just did" what they did, they don't remember any conscious decision to hit/slap their partner or their child. Therapy focuses on mindfulness, deep breathing, hand relaxation, posture relaxation, amidst various stressful stimuli. Such people are often told to avoid all triggers (if social anxiety is an issue, then either get medication to treat it, or avoid social situations as much as possible).