It prevents you from leaving certain areas of your house, or work place, or wherever you are when you've "safe-zoned".
This is the most comfortable place in the entire world. Nothing bad can happen to you when you're in the safe zone, even if you're watching the creepiest movie, it's always best to do it from inside your safe zone.
Can be a hazard at times. If you safe zone your bed, and need to get food, it becomes a problem because you're rendered unable to leave. Something inside of you wont let you leave the safe zone
On rare occasions, when you've safe zoned too much, you begin to safe zone when you're straight, creating a bit more of a problem if you need to get up and out of your house to do shit.
The act of safe zoning is so infectious that soon enough, your friends will be doing it too. It's fun when you've all safe zoned together.
"Sorry man I safe zoned as soon as I got home, we can hang out later on"
"Man, I can't leave"
"I'm in my safe zone, can you get me a drink?"
"Just get up and get it"
"I cant. I can't leave this room"
A "safe zone" can be a phyiscal place or even a state of mind - one can be "outside their safe zone" when standing in front of a crowd, giving a speech.
He's very familiar with the town he lives in; therefore, a sudden move would likely take him out of his safe zone.