Yes they are impressionable. And hopefully this punishment makes them realize what they did wrong and they never do it again. And hopefully any other parents/children who read about this will learn from it as well. We can't just give them all trophies for saying they are sorry. Even though that's what culture and schools do nowadays.
...and apparently their social and educational development is already in a bad place or they would not do such things.
This is a lesson. Nowadays there aren't many going around b/c everyone is too sensitive and have to be politically correct. I applaud those who made this decision.