Amazon will be the first to tell you that listings do not belong to anyone. They are free for anyone to use as long as the seller on that listing is in possession of the product identified on the listing and has obtained that item legally.

However, trademark infringement is illegal. If you own the trademark of the item you are selling, and there is a seller who is jumping on your listing and not fulfilling any order, I would consider that IP infringement due to misrepresenting that you have a trademarked item on hand but are not fulfilling anything and, therefore, hurting the consumer experience of the trademarked item. You could use brand registry to report this.