It has been around for a while .
The photos are not photoshopped/ editted/ cut or faked as far as we can tell. It would be one of the easier things to prove by people that work in such professions and don't think anyone has come forward to say so.
I think all the arguments put forward regarding the angles and perspectives of the photos have been corrected or rather explained why the author of the link you provide is wrong.
The theory also suffers from much of the same problems as others, who moved them , how did they move the bodies , what did these others that killed and moved the hikers bodies eat , where did they camp , what did they use for warmth , where are their trails , why did they pitch the tent on the slope and how did they manage to do so without leaving their own tracks, who made the footprints of the 9 hikers in the same footwear that they were found in? Etc
Who or what outsider could even know( and remember this is 1959 ), that the snow was of the correct make up on the day that the footprints were made and that those footprints alone would survive until the searchers turned up , not only did these footprints survive but they would give enough detail that the searchers could tell that the people that made them were wearing socks and toes could be made out in the prints and the direction.
It is incredibly difficult, if not impossible to make footprints and leave no trace of your own , you can't predict what will be left behind and what will show and won't. The snow has layers and anything dropped at that moment in time stays there, there are no signs of anyone else , animal foot prints are found on the trails as are some Mansi tracks and the early trails of the hikers . We have the tent on the slope , footprints down to the ceder , bodies, broken branches used for flooring ( separate to the den flooring) and a fire at the ceder . There are various broken branches that were used for flooring at the ravine ,it now seems to me that these small trees can be snapped with little effort during winter, there is a case file account of this and a modern one. There are also the scattered socks, shirts, jumpers and trousers in between the ceder and ravine. There is nothing else to place an outsider there.
The raised footprints are one of the hard facts of the case that places the hikers on that slope . The only other possiblity is that 9 outsiders walked in socks and created this path to the ceder , or perhaps 1 person did it 9 times ? But this individual was clever and did not walk back up the slope , he walked a thousand miles and came back in a loop or he had the latest soviet union anti gravity device that made him hover?