It's not about having "a phone" killed. It's about the ability to have phoneS killed. Plural.
No. I intentionally decided against the paranoid option.
What purpose would it serve for the NSA to brick a bunch of phoneS at one time?
Other than making a very big, very public story? Which would get a LOT of airplay in the media.
If the NSA needs service cut in a specific area they can already do that.
You mean like how the installation of clothes-penetrating image scanners wouldn't need to be implemented when dangerous objects can already be better detected by more conventional screens and selected pat-downs? It's for the same reason the U.S. has toyed with the idea of an Internet kill switch and a way to disable cars remotely: when one becomes addicted to power, the ends of power obtained justify the means of obtaining it.
The federal government does not particularly care what temporary effect such measures will have on media and the general public; the ability to do it at all justifies (to them) its implementation.