This happened during a wave of rain, followed by about 4" of snow and very cold temps plus high winds. Real temps got down to about 0 degrees F, and that's not accounting for wind chill. These guys picked about the worst time to go exploring in Shining Rock. Current reports are sketchy but stated the pair were lost with no map, compass, or GPS.
The Shining Rock area trails are unblazed and it's notorious for having undocumented rabbit trails and shortcuts. People unfamiliar with the area commonly get lost.story from Smoky Mountain News
They were able to get a fire going, which is darned respectable after the 2+ days of soaking rain that preceded the snow. One story said they constructed a shelter, while the above link says they found one. There are no established shelter structures in that area, so I'm curious to hear more details when they come.
My net takeaway from the various (early) accounts is that these guys weren't highly skilled, but they did manage to hold on in some extremely challenging conditions. Ultimately it was their ability to communicate for rescue that saved them.
I expect they have learned a lesson.