The FBI isn't telling you this so you could protect yourself from the government. They are telling you this because they know how easy it is for someone else to

The FBI isn't telling you this so you could protect yourself from the government. They are telling you this because they know how easy it is for someone else to take control of the camera and make your life hard. So it is a common sense step for you to take if you're concerbed about security. You took a pretty huge jump from that to the FBI listening to your mic.