I don’t see the problem. When I was a student and at an excavation, each of us in turn had a duty to empty the buckets that were used as makeshift toilet into the cesspit. Those buckets had collected the full day products of about 20-30 students. Not just one excrement. A whole giant bucket full.
As long as you don’t eat the stuff, don’t smear your ass with it, but do wash your hands afterwards, there is no problem. I agree with Mort, hygiene concerns have gone to ridiculous extremes.
I think having to clean this was just a good lesson for these kids. If you befoul your surroundings on purpose, there is someone who will have to clean it, that is the lesson they learned. They all learned from it, including the unknown perpetrator.
Also, I think it is rather American to cry out if little WASP kids have to clean fecal matter, while all would probably find it perfectly appropriate if an Hispanic janitor would have to do it.