Because with their budget they can afford to induce artificial demand and thus exert control over the signal, fooling adversaries in the process.
If you were bin Laden, maybe you might not have been caught unawares helicopters were about to crash in your garden. It's not like you didn't know they were looking for you.
I can't think of someone that the Pentagon or other agencies that this applies to that their adversaries would not know they were the adversary. This might be more relevant than you might think
Plus when it’s time to go Mutually Assured Destruction, ie to those capable of attacking the US mainland, I’m going to assume they would be doing all this from whatever the successor to Mt Weather is.