That's actually pretty digusting. Not only what they had to do, but your lack of sympathy towards them.
How is that an effective form of punishment whatsoever? All it does is increase their risk of getting sick, especially if it's in the gym.
If I sent my kid to a school I wouldn't expect them to end up eating food off the floor.
The parents have every right to be outraged. Perhaps they overreacted a bit, yes, but I'd be mad as hell too.
PS: Can you please give the topics objective names?