Many have remarked on the oddity of Zolotaryov's presence in the group and the possibilty that he was a secret agent by profession.
I have no problem seeing his involvement as just another weird circumstance having no particular bearing on the matter, except... what if his sole job was to ensure a group of random campers were at a certain location at a certain time?! Certainly his haste on the expedition has been noted from diaries.
From my reading of the political circumstnces of 1959, I see it as an almost certain bet that Russia were coninuing testing in breach of the nuclear test ban which they had pushed for. How else were they going to catch up with America in capability? Naturally, they would have to relocate their test sites to do so and testing of high yield devices would be out of the question.
Is it so far-fetched that Russia would seek to understand the killing capacity of low-yield devices by testing in a new test location over the Urals, well away from prying foreign eyes?
In this scenario, once the campers were in place, Zolotaryov would have realised the situation as soon as the first explosion occurred and would have likely understood he was a dead man if he didnt seek shelter. In any case an explosion would explain why they all left the tent in a hurry. In the darkness they potentially became separated but what if, and here's the kicker, the group that ended in the ravine turned out to be the unluckiest ones when the walls of the ravine acted to concentrate a subsequent blast? The dead group in the ravine would be unable to yell their location to the surviving group who resorted to climbing the largest tree as a lookout in the hope of spotting their comrades.
Zolotaryov was found with notebook in hand and the Colonel who discovered his body seemed genuinely disgusted that he had written nothing down. Perhaps his emotions, knowing he had suffered radiation exposure had sapped his will to obey his task.
The complete control over the case from highest levels would simply reflect gathering of evidence to conclude the objectives of the test.
This seems to me to pass the Occams Razor test.