Haha, how cute. For the record, pet stores carry plenty of things which are bad for, if not dangerous for pets.
Snakes can't digest wood. MOST things can't digest wood last I checked. Wood and bone are very different substances. Digesting wood takes very special stuff (usually specialized bacteria) which snakes lack. Bones are comparitively easy to deal with.
Chances are unless it's a really large, sharp and/or jagged piece though, he'll probably pass it just fine.