Yep ... they were full of it!
They always are!
Guards on the shelves would be a good idea and would help to a certain extent ... just remember ... they will use the guards as chew toys also.
Guards can easily be made by taking 1" x 1" or 1" x 2" strips, cut them to size. The sizes mentioned can be easily cut with a hand saw. Remove the shelf. Pre-drill the holes (to keep the wood from splitting) and use wood screws, not nails, to attach them to the three outer edges of the shelf and reattach the shelf inside the cage.
Drilling holes and using tight fitting dowels is also an option, if you want to avoid using screws or nails.
Shelves with guards will cost you more than regular shelves and you will have to replace the guards as the chins chew them, but it is well worth it to learn how to build and replace them yourself.
Jo Ann