@greatninja3 Just like the nuclear weapon, this power isn't supposed to be used, but only to intimidate in order to preserve peace.
Si vis pacem, param bellum. You know...
Having this power was actually how Kaname managed to stop gangs wrongdoings after annihilating the Eights. And obviously, gangs take that threat very seriouly, so they won't act out of line and thefore, Kaname never had to use that privilege ever again