Competitors are just other entrepreneurs who are trying to solve the same problem as you. You should be on good terms, not paranoid.
I remember one young entrepreneur demoing his wares to a group of us, and this a-hole said "Wow, that's a great idea. We are going to do that! I'm going to ring X-famous-person who would love this now!". This was a successful, internationally known entrepreneur with huge resources behind him. Everyone in the room was just shocked. And he was serious, and didn't even offer the entrepreneur anything, not even a job.
If he went and demoed his private, unreleased product to a bunch of potential competitors, then I'd say that's taking trust a bit too far.
The meeting was actually organised by the city to set up a cluster for our industry, obviously nothing came of it after that debacle!
It is much better to set up legal rights through a patent or an agreement than to rely on strangers to follow some vague business ethics code. Many successful businessmen became successful because they broke such codes.
I elaborated further in a comment on the original thread.
If you are sane normal adult you should be able to talk to someone without giving out any secrets.
I think this is one of those posts where the author is not really looking for advice but secretly bragging. "Look at me I am so successful I have my much larger competitor begging to talk to me and I just told them to f off." Well there is nothing wrong with a little bragging if you have achieved something significant, but then just be honest and brag, don't couch it into a question.