I can’t see a legitimate need to cut off radio and TV in an emergency.
Quite the opposite in fact.
50-60 years ago it was a legitimate policy. The Soviet bombers could have used strong signals to home in on our cities, much as the Japanese had done with the commercial radio signals from Honolulu in 1941.
Google CONELRAD.
Unless of course it was a political emergency like civil insurrection or someone trying to enforce the constitution. Or people wanting to -gasp- vote.
A situation they are obviously preparing for.
They interrupt broadcasts to issue emergency announcments. A system of this type has been in place since the 1950's when it was called CONELRAD (CONtrol of ELectomagnetic RADiation). A crude system compared to its successors, one of its purposes was to impede enemy bombers using commercial broadcast signals for direction finding.
Later systems were called EBS (Emergency Broadcast System) and EANS (Emergency Action Notification System). The mission of the systems evolved from defense against nuclear attack to a broader range of civil emergencies, and the methods of dissemination and control became more sophisticated with successive implementation of teletype, leased audio lines, satellite and finally internet distribution.
99.99999% of all EBS tests are done on a weekly basis at each broadcast station. The lower-level stations in the hierarchy also have to log receipt of test messages from points higher in the hierarchy. But a top-down systemwide test is very rare.
30 or 40 years ago, they did one at a time that the primary distribution of top-level notifications (i.e., directly from the DOD or whomever -- this was before FEMA) was done by teletype.
Somebody at HQ loaded the wrong punched tape into the master transmitter; namely, the REAL emergency tape! Most stations down the wire had the good sense (I guess!) not to broadcast their REAL emergency scripts, probably because it happened at the exact time the test was scheduled.
A prime example of Murphy's law. I suspect that someone scribbled the names of the various scripts illegibly in pencil on the little coils of black paper tape ≤}B^)
What if some mole inside the US Government gets hold of this technology and turns it on them and the general public? Just a thought — those in charge don’t always keep close watch on stuff, an example being, the WIKILEAKS memos.