^Yes, it was foolishness, but that was the point -- the Platonians were a decadent culture who got their jollies by forcing people to humiliate themselves with absurd antics. They see it as comedy and fun, but they're violating people in order to make it happen, and that makes it sadistic and cruel. It's that dark, horrific undercurrent beneath the low comedy that makes it potent.
This is topic drift, but what I like about Plato's Stepchildren is that it is, like you say, a parable about bullying, a topic that is of particular relevance today with school shootings and the like. That society did in fact operate like immature and amoral children.
Also, I found it poignant that the midget, in the end, who was lowest on the pecking order, was the one to finally realize how abusive his society was, and turned around and fought back and won.
It reminds me of Sally Kellerman's final redemption at the end of Where No Man has Gone Before.