I don't understand why so many bones could be found in the latrine. To me that indicates either that humans commonly ate bones during the middle ages or that latrines were used not just for toilets but as cooking-scraps dumps as well.
What I learnt from a friend of mine who studied archeology: latrine was not a strictly separated place. Instead, there were more generic "trash places", where latrines usually stood, but a lot more unwanted things ended up, too. Including broken pottery, bones and fruit stones.