"You can't get locked out."
Well, you can, it's called death. But as far as I know, there's nothing to fear because you can't be killed "from the other side".
Regarding the mythical silver cord: The idea is derived from the umbilical cord that is keeping an unborn alive. The umbilical cord connects the body of the unborn with the body of the mother. But you need to consider that when you leave your body behind, you are not its mother, and the body is not your child. It's not the same principle.
The term "silver cord" is derived from Ecclesiastes 12:6-7 in the Bible.
One theory is that the cord is an imagined manifestation of the fear of losing the body.
Think about it logically: Death as we perceive it is initiated by rendering the physical body useless. Nobody cuts an invisible silver cord. You need to cut the body, literally. So, death is initiated on the physical side of things. Leaving the body while it's still alive somehow means that you are safe. So the question is: How is that possible?
What actually is it that keeps your body alive when you're "not home"?
The logical answer I found so far is that you never actually leave your body, but instead, expand your consciousness by shifting your focus. It's like sticking your head through a window while keeping your left foot in water.
What do I mean by "shifting focus"? Well, you only think that you are where your body is. In reality, you are also where your body is not, because an ISBE is a singularity, which means it doesn't have dimensions. The ISBE is not bound to space and time, because it's not the body – it's consciousness. So, in reality, you are consciousness that is focusing on the space and time of your body constantly. You are not there, you just look there. And when you remote view, you look somewhere else.
So, let's come back to the question what keeps your body alive. Why does your heart beat in the first place? Does the soul "drive" every beat? Here's a question to meditate about:
What if your heartbeat is just a chain reaction, and you are riding it like a wave in the ocean?