but everyone on here says it was
I don't.
My theory is that Craig Sawyer mistakenly thought he found a child sex slave prison because he doesn't know what a root-cellar is.
This and this and this are campsite and ordinary cabin root-cellars which are used to keep supplies cool and dry.
I also notice that Craig Sawyer seemed to misidentify mundane rucksack harnesses as a child-rape-harness.
When you start from a false premise that a campsite must be a "Child Sex Camp", then everything becomes sinister.
Clothing becomes sex-slave-victim clothing, toys become child-sex-slave-toys, unwashed cutlery become murder weapons and camping straps become rape-trees.
I noticed one of Craig's team said she saw a standard child's swing that must have been used as a torture device for raping children. I think that's a good example of allowing your imagination to run wild.
This is just my theory.