This most certainly must be sarcasm. You wouldn't seriously suggest that a student could not wear a NRA or pro-gun t-shirt? A history teacher shouldn't be allowed to explore or demonstrate examples of firearm technology and the real impact they've had in wars? Or, discuss the value of armed riflemen in preserving our freedom? We should promote illogical ideology in the name of political correctness by complying with it?
As to changing the laws. These are either the actions of over zealous administrators or school policy approved by elected school board members. If this type of policy concerns you you should contact your school board members. Most school policies are available today online at the district websites.