The lesson here is that criminals attempt to hide their bombs using everyday, innocuous objects that do not draw attention to themselves. Magnetic signs with light-up Mooninites do not fit the profile. (If you want to ignore the profile, than yeah, anything could be a bomb. It could be someone you know. Someone you trust. You might be a bomb and not even know it.)
I wouldn't be so flippant,its said that the soviets used booby traps designed to look like toys,and a one inch wide sheet of plastic explosive in a claymore like device designed to attract attraction especially kids is a real terrorist possibility