Years ago when I lived in Saudi Arabia someone hijacked a plane. They tricked the hijacked into thinking there was a problem with the aircraft and that they would land in Bahrain to fix it. They actually landed in Dhahran. A military man dressed as a maintenance man boarded the plane and ultimately killed the hijacker with a fire ax. The news reported, someone tried to hijack a plane and we killed him. No hijacker name or cause. They had it figured out in the 80s.
Why limit it to school shooters? This could apply to all acts of mass violence without regard to the tool (bombs, knives, etc.) or venue (theaters, sporting events, etc.).
Your point of denying fame is the key as it denies the motivator his goal.
My first thought was why a law, but you are correct, the news media has no conscience or sense of public responsibility.
One critical question I have is where did you come up with 33%?