It's not a question about "giving legitimacy" to the KKK. They exist, and existed. There's no arguing with that. I highly doubt that this play was meant to lend any sympathy to the Klan.
There's a certain kind of learning that happens with "doing," which doesn't happen with a book discussion, for example. Being a villain in a play can be just as eye-opening as being a hero or victim. I don't question the right of that parent to object to the play or its lessons--but it seems like the school acted rashly in cancelling it.
And for the writer who thinks that this is an inappropriate lesson for 7th-graders: students this age are capable of handling much more than you give them credit for. Most of them have been reading about the Holocaust, American racism, and other difficult topics for years by this age.
Please explain the inappropriate content below.