Well, it’s not the rock itself that’s pushed by the wind but broken up sheets of ice. The flat ice pieces push the rocks along, or the rocks are embedded in them and scrape along the ground as the ice pieces are blown along. In other words the ice pieces sort of act like sails for the rocks.
Something else to keep in mind is that when this happens the ground is probably wet, not dry as in the pic. I know from experience that the ground out there turns into a slippery mud when it’s wet. This would act to lubricate the path that the rock moves along. Their theory seems plausible to me.
You have to understand the wind there is pretty intense, up to 70 mph on a regular basis. Even on a nice calm day there was wind out there, much more so that I ever expected.