Should parents be sued for asking questions about their schools management?

Sounds to me as if this school is shooting itself in the foot. There is no way they will win this case, unless their allegations of defamation and libel are true, which seems unlikely. And to answer the question, yes, charter schools should be able to sue, but only if they have a case. This doesn't sound like a case to me, and public schools are different, naturally. Any activity funded by taxpayer monies would not have that recourse when taxpayers are only making sure their money is not wasted. Private organizations have that right, even if it is frivolous.