There is no 'perfect' substrate they all have pros and cons. Feeding on substrate it is inevitable that the snake will eat some. As pointed out feeding in a separate container can cause issues too. It is always a moment of the lesser of two evils. I have had an animal (one eyed with remarkably poor aim) get a full mouth cyprus mulch and have a digestive blockage (I have the x-rays and vet bills to show for it...) Personally I'd rather see a royal eat fine coco coir than wood chips. Paper would be safer than either but it is a pain to clean and looks well like paper and is very poor with humidity issues (hygroscopic it draws humidity from the air) No great answer why there is so much debate if it was a clear choice there would not be controversy.