movie
I would suspect that the child is interested in the Hobbit because the parents probably let the child see the Lord of the Rings movie or there is actually an animated "Hobbit" movie. I would simply ask the parents if they wanted their child to read this book. There are much better choices out there for a third grader. There is some violence, but so tame compared to what some parents allow their children to be exposed to these days.
My concern about the child reading this book would be the fact that the concepts were out of their level of comprehension and therefore wasting time reading such a book, rather than something more at their level of understanding.