So your situation is something you saw on 24?
Unless the guy is live streaming 24/7 then your goon can brick the whistleblower's phone with an actual brick.
Also, look at real whistleblowers and try to explain how the government would have stopped Snowden with this power? Stop imagining spy drama fiction.
They wouldn't stop Snowden (only) with this. They would, however, be able to keep the story about what's happening in Ferguson, MO (for example) from ever trending on Twitter, simply by killing every phone talking to a particular tower.
To be clear: I'm not suggesting the Feds (black helicopters and all) would do it. I'm suggesting the enlightened minds of the Ferguson Police Department, who have already demonstrated the depth of their acuity, would be perfectly willing to use such a tool, if it were (somewhat) legally available to them.