a fully infected/mixy rabbit, aint going to run anywhere, you can normally just walk up and wack them, so if its showning signs, its either just getting, or immune so see how it goes,
why bury or burn???? mixy is passed by flea's, not direct contact between rabbits, can see the point if its full blown mixy, but anything else, Ive stuck in freezer and used, no problem
Now you've asked I've no idea why, it was advice given to me by my Dad some forty years ago and it's stuck with me. He was a pest controler for WarAgg after the second world war so I assume it was their policy to do