This is all nonsense. Talking about your ideas with others begets more ideas. I say, if someone else steals your idea, good for them! If they're a good writer, what they do with it won't look anything like your story anyway. And if they're not a good writer, why do you care what they do with your idea? And forget copyright--leave all that up to your agent and publisher, although my guess is the hoarders rarely get to the point of having an agent or publisher.
I'm something of a perfectionist, but once you've gotten your story to a point where more work on your story doesn't change the story's quality, move on to something else. There's usually a natural point where if you're paying attention, you realize you've pretty much reached the limit with the story you're working on. If you spend longer than that on it, you're just gumming up the creative part of your mind that needs new things to work on.
You should have so many ideas that if one doesn't work out, you have a hundred more to pick from. The thing to do about ideas is not to protect them, it's to stoke the furnace in your mind that produces them. And just as you don't gain strength by resting your muscles all the time, but by using them vigorously and often, so it is with your creativity. Write lots of stories, poems, letters! (Blog posts!) Keep a notebook with you to write down story ideas whenever they occur to you. If you have a funny or frightening dream, consider how you might adapt it to written form. (Lots of my best ideas come from dreams.) And join a writers' group, where you can discuss all sorts of ideas with other writers!
Written by Nicholas Bruner, cross-posted at The Ballad of Nick's Blog