At the end of that run it looks like there are mixed segments of walking and riding, with the telltale "buttonhook" pattern at many transition points. The question is: why switch back and forth? It's very remote, so doubtful that anyone would be out there.
I looked at the area on google maps, but couldnt find any landmarks that might explain the behavior. Maybe they were looking for a good photo op?
I think it's very telling that all of the cheating is at night and in the rural, open American west. Too many people around in CA to start, then they get out in the open, and all of the blistering paces are at night with no one around, and you can see exactly when they slow to normal pace as soon as they come into towns.