The account in the Bible of the demons who were cast into a heard of swine and they all ran off a cliff, gives them license to say that if demons can inhabit swine they can inhabit anything.
Back in the day, it was common belief that demons were lurking inside inanimate objects and were waiting for unsuspecting JW's to come along so they could "demonize" them. As a kid during Halloween, I used to ask why our neighbors or the kids at school weren't demonized by the ghosts, ghouls and jack-o-lanterns they had as decorations on their houses and kept in their closets all year. I was told that Satan already has them in his clutches and wants to get us away from Jehovah and he is like a "roaring lion seeking to devour knowing he has little time left."
Magical thinking is part a parcel of the JW mindset. Living forever in paradise with lions that play with beach balls, the idea that Jehovah is watching them at all times and is sad when they miss a meeting and the entire world and an evil spirit enemy is plotting to get them makes them feel that they are the center of the universe because of their special religion .