Hi and thanks for the criticsl thought. I too have been buzzed by a jet and it did not completly unhinge me either. However, I wasn't on a snowy hillside, and the jet passed once and was gone. If the photo of the glowing orb was a flare, this might suggest an intention to return for practice putposes. Vietnam was heating up and Russia supplied the North with aircraft.
The hikers left quickly because they could not talk their way out of an iminant threat of destruction. What else would make a group of sane college educated experienced trekkers say as a group, "We have to go...now!"? Bombardment, snowslide, uncertainty of others intentions is compelling to me. Looked at from another perspective. why would it be foolish to remain in camp and wait it out? Answer, we can't be seen and maybe we are in the wrong place.
There seems to be lots of possible reasons. E.g
Forced out
Infrasound
Bomb
Poisonous gas
Etc
The more you look at the details the more you uncover
As for the flares (which were commonly used to mark air strike targets or landing sites for paratroopers during WWII), it depends on the specific setup and people. That means I would not be scared as I have always lived near the airport I never experienced war as such. On the other hand, it is fully understandable if a dropped flare causes panic to people with experience in war zone (just like Semyon) or anybody familiar with bomb testing procedure (Kolevatov). War trauma can trigger much worse and violent reactions when "experienced" again, let alone the attempt to flee and find shelter wherever possible.
As for the time frame, 1959 is exactly in the middle of a process of introduction of MiG21 aircraft and Vympel R13 Air to Air self navigated missile (copycat of US-made Sidewinder, indroduced in 1956, Soviet version in 1961). The flares are ofter used as a countermeasure and would be used during a training (probably with disarmed missiles) because they lure away the infrared sensors of a missile from a target aircraft. Could hva ebeen dropped somewhere by accident.
I would label this theory "plausible". Above mentioned definitely happened somewhere in the USSR in 1959 and around that time. We cannout prove it happened at EXCACT time or place without supporting documentation.
Forced out - plausible, by whom? (no outside party - Semyon or Thibaux are my favourite suspects because of the clothes and shoes they were wearing unlike the rest of the group, outside party - miltary/paratroopers?) motive?
Infrasound - seems inconsistent with the evidence and unlikely to trigger the death of 9 people...but might be interesting to study further
Bomb - no traces of that in the area, bomb threat (real or not) still plausible, with or without flares, but Ivanov mentioned lights in the sky and burned tree tops that would support use of flares, maybe and aerial explosion? night bombing training?
Poisonous gas - plausible, source unknown - chemical weapons or natural source? would be interesting what kind of substances could have been used in 1959 and how would they affect the victims