It's not impossible for the issue described to happen. Sometimes the most state of the art equipment gets blundered. This particular issue is as old as rotary wings. When low to the ground, it becomes possible for rotor wash to get drawn back in as rotor feed in a vortex.
The end result is effectively a free-fall… Or faster-than-freefall scenario that slams the helo before much of anything can react.
Now… Is that what actually happened? … That, I don't know. They at least came up with a halfway believable story. You have pilots and operators going into an organic situation and then something goes pear shaped.
That said… It is an awfully convenient coincidence that we don't like to believe in.