I am not exactly sure where Knife ridge drops you out of the resort. Reagrdless, if you look West at the map you can see where the highway splits the canyon. They probably dropped somewhere towards the south end of the resort and to the west. Probably 2-3 miles from the road at a guess. You can see that if you go due North of the ski area it does get fairly flat. The caveat is that 'bilers roam all over that area, so there are bound to be well established trails at some point. Of course they were there during heavy snowfall, etc. It wouldn't make life easy, but you can certainly get out. It also sounds like it was a hell of a storm when they got lost. The probably did not intentionally go out of bounds. I would guess that the lack of experience in this sort of situation was probably their undoing. Most things you hear about being lost in the backcountry is to stay put. That is great on a summer time hike, but in the winter if you are not prepared to spend the night out, it's the worst thing you can do. At that point, you need to pick a direction that would get you back to safety. In this case the resort or highway.
Also, reading into this more, it sounds like one of them may have gotten buried, leaving the other person by himself. As one boarder was found by a tree with his board nearby. Sounds absolutely horrifying and sad.