What interested Jon was people being turned into furniture. He couldn't wait to turn someone into a sofa, a chair, a floor lamp, or even a bed.
But there was a price to be paid for Jon's fetish fantasy: wishes couldn't be reversed. So if someone became a rocking chair, they'd be stuck that way for rest of their lives, or as long as that piece of furniture would last. Jon wanted his fantasy to be fulfilled, but not at the expense of other people's lives.
So, he decided to make a precautionary wish. "I wish ..."