You missed something.
"It wasn’t explained why people from different walks of life should dream themselves into a setting of scientists stuck at a spooky, snow-bound lab."
Ah, but it was! Just sneakily. Upon one of the dreamers waking, they glanced at a list of films to watch. What was on that list? The Thing... a movie about scientists stuck at a spooky, snow-bound lab. Along with Mo34S, a movie about Santa. The dream simply drew from the movies she'd fallen asleep after watching.