Says you...But, I don't want MY and MY FAMILY'S life relying on what YOU deem as a 'serious enough threat'...
So some dumbass gets his hands on an oxygen-acetylene torch and some tanks and tried to cut the cables on the Brooklyn Bridge but decides at the last minute there are far too many to cut in open view to do any damage...so he just lites up the tanks instead and blows himself and other innocent passersby to Kingdom Come...Bada Bing..Terrorist threat now a suicide bombing which kills many people and disables the bridge for a certain length of time...
An asteroid could hit the planet, too. That doesn't mean it will, or that you should grant the state carte blanche to do whatever is necessary to minimize that risk.
Conservatism is dead. And the GOP killed it.