As a local, were they 15 miles down the wrong road ?
How far beyond that to a cabin, town, etc. ?
One should be able to walk 2 to 3 miles per hour unless the snow was really high...without snow shoes or a x-c ski.
They are now reporting the trackers found a pair of pants that belonged to James Kim.
Most people can barely manage walking at 2-3 miles per hour on pavement. In the woods, over rugged and likely hilly terrain, in snow, he would probably have been lucky to make 1 mile per hour. And keep in mind that he'd been out there for something like 6 or 7 days already, so he was already likely to be short on sleep, short on hydration, and short on nutrition. On a road or clear trail, rested, fed, and hydrated, 2-3 mph would have been more likely, but it doesn't sound like he stayed on the road for too long.