It's not supposed to be a gotcha, it's supposed to be an example of the hypocrisy of the government.

Similar example Ohio legislature makes it illegal to drive with any THC of Cannabis products in the passenger compartment to crack down on people driving high, but there is nothing to prevent you driving with an open bottle of prescription opiates or benzos and popping those while you drive.

Bad choice of example, then. Restricting things that are uniquely and critical to planning and executing school shootings is a highly desirable outcome for regulation, in the eyes of a society that desires its youth to grow up without constant threat of murder at their mandatory educational institutions. That desire is not particularly uniform in the U.S. right now, in contrast with much of the world. Choosing murder sprees as an example supports regulations that have societal safety benefits, which is the opposite of what was intended. Perhaps a different example might have the desired effect?