This is not a lesson that is to be taught by the school. If your university told you it was your ‘lesson’ to clean all the toilets one week would you have done it?
If this was because someone out of the group of students I was part of had deliberately shit in the classroom, I would not be happy to carry out the task, but I would find it acceptable as such.
...Simply because defecating in a classroom to taunt a teacher is so gross, that it justifies the setting of a stern example in my view. Sorry then if this also is tough on people who were “only” onlookers, but they won’t die of it.
And mind you, since they stood by but didn’t interfere in this gross defacation act, they probably are not that innocent. And now they learned that such extremely gross things just cannot be tolerated and lead to harsh measures. They won’t forget it.
It in fact is similar to the case where onlookers of a rape are prosecuted. They didn’t rape, but they are not innocent.
That’s the whole point. That class learned that there are certain things, that go way too far and are not normal. And this will lead to unpleasant countermeasures.