Your editor hasn’t spent much time on today’s National Student Walkout mostly because there has been plenty of coverage and commentary from other corners. Yet I find myself writing briefly about the protests by high school students on behalf of gun control laws spurred by last month’s massacre of 17 students and teachers at Marjorie Stoneman Douglas High School in Parkland, Fla., because the event inadvertently intersects with an issue school reformers continue to deal with badly: The debate over…