I don't subscribe to this theory. If you're going in there as a 23 year old then you're gonna have guns or you're gonna die. Which they all did. So maybe I _should_ subscribe to this highly implausible theory. But still no. Reason being that the opposing force is not going to come towards you and brutally kill (which _did_ occur) with the inevitable cleanup which just can't happen if a foreign force has done it. (i.e. CIA type of thingy). No. Just no.
Unless we are to believe that it wasn't only the 9+ Dyatlov group who died but also a bunch of CIA operatives too(who were removed - they had over two weeks to cleanup). That doesn't happen. Unless there's some sort of "entente cordiale" [I hate/ dislike / actually like the French] going on between them. Very unlikely. So we're back to square one.
What I think is much more likely is that the CIA were nowhere near any of this and it was just Mother Russia protecting her communist state and the 9 were expendable. They were suspected of something and were brutally and sadistically murdered. That is a trait of a communist country after all : as can be graphically seen right now ........ elsewhere.