Ettins have a chemical in their bodies called "Ettin nitrate" which causes their brains to be unable to see gadgets when in the presence Ettin Home scent. The Ettin home room stops the smell of gadgets from existing in that space, which prevents them from trying to hunt down gadgets that they already brought back and can no longer see.
It's interesting to think that shee probably did this sort of thing all the time, to fine-tune the behavior of albian and ark fauna. Though lorewise I like to think they were a bit less cruel about it.