See, that's actually quite reassuring to me, given the alternative. Of course I understood that the "hideous monster" at the end was the person after being compressed through the hole--there really wasn't any other way to interpret that ending--but I actually felt relieved seeing that, since it implied A) that there was an end to the tunnel, and B) the people hadn't just walked into the tunnel and disappeared, which I find much more terrifying.
Honestly, the end to that story is not nearly as frightening to me as the middle. Frightening, yes, but as frightening, no.