We can't always supervise. If I supervise my snake right now, he won't eat. :[

I've read that story before actually. If you pay attention to what it says, it was a RESCUE.
The rescue was needed in the first place because a lazy owner left a rat in the cage.
Simple as that, don't do it and you'll probably be ok. :]

Of course, theres always going to be a risk, but thats part of having a snake.