The Gaume and Puzrin article about the slab avalanche seems very compelling, but still somewhat incomplete. I'm considering the following:
1. Military testing of weaponry that are either Sr-90 dirty bombs, or conventional bombs spiked with Sr-90 for analysis of the blast pattern, trigger the slab avalanche.
2. Due to where the bulk of the avalanche hits the tent, and what exactly was under each person at the time, Dubinina and Zolotaryov experience crushing chest injuries, and Thibeaux-Brignolle experiences a skull injury.
3. The entrance to the tent is blocked, so the other hikers cut their way out and rescue everyone.
4. They're now exposed to the wind, possibly in the vicinity of continued ongoing military explosions, their shelter is useless, at least three of the party are seriously injured, and they are likely concerned about another avalanche. Moving downhill to the tree line, starting a fire, and making new shelter seem like the best alternative. They have limited time and ability to dress where they are, so they leave in a hurry.
5. They make a fire at the cedars.
6. They begin digging a shelter in the ravine. The three most critically injured people are put in the shelter. Kolevatov stays with them. The three eventually die from internal injuries, and Kolevatov dies of hypothermia.
7. Dyatlov, Kolmogorova, and Slobodin attempt to return to the tent once it is safe. They may have intended to fetch more supplies and return again to the others, or they may have intended to dig it out, set it up again, and signal for the others that it was safe to return. Before reaching the tent, Dyatlov and Kolmogorova die of hypothermia. Slobodin may have had head injuries from the original avalanche and tried to ignore them, or he may have fallen, injured his head, lost coordination, and injured himself further.
8. Doroshenko and Krivonischenko stay by the fire. One climbs a tree, either for firewood or to help scout for the tent and the other three in the party who are returning to it and falls. Both eventually die of hypothermia.
Meanwhile, the bodies have all been contaminated with Sr-90. The military has no idea anyone was in the vicinity of the tests. (Yes, the group received permission to be there, but in large bureaucracies, the different parts often don't communicate efficiently with each other.) The military doesn't learn of the hikers until after search parties are in the area, at which point it is too late to do anything. (If this had occurred as I suggest above, then I maintain that the military would have wanted to make the bodies and the tent disappear to avoid the negative media attention, but they had no time to do this.) After the first five bodies are discovered and removed, the military quietly suggests that Ivanov should take a Geiger counter with him to ensure everyone's safety, and they later pressure him to close the case with no mention of glowing orbs in the sky (a.k.a. aerial explosions.) The area is closed for years to give the bulk of the Sr-90 in the area a chance to get carried away by snow melt.
Alternately, the slab avalanche happens without military involvement, everything still plays out as above, and at a later time but before any significant additional snowfall could cover the bodies, military bomb testing dispersing Sr-90 manages to contaminate, at a minimum, the four bodies still in the ravine.
As much as I would like to think that there's an explanation not involving a military conspiracy, I still can't otherwise explain the presence of just beta contamination on four of the hikers' clothing. (I've found no record of the other five being tested, so it is possible, and I think most likely, that all nine were contaminated together due to a single cause.) I can think of no natural source, and it seems very unlikely that occupational sources would be pure beta emitters and not a mix of alpha, beta, and gamma. I don't believe lantern mantles could possibly be the cause, or alpha contamination would be observed. Occupational contamination might have affected one or more pieces of clothing worn by one hiker, but it would need some mechanism to spread to all the clothing tested.
Additionally, I find it incredibly unlikely that a search and rescue team in 1959 would even consider bringing a Geiger counter. Even today, in the US, it is not standard practice. People on a S&R team would want to conserve weight by not carrying any unnecessary equipment. That radiation was ever detected at all implies strongly that someone knew that there was a reason to look for radiological contamination, which points back to some kind of state conspiracy.