Those are some great questions. Again, I'm not an attorney, but I'll put my opinion out there.
The experience level of coder is irrelavent. Knowledge of copyright law by the coder is irrelavent. Either the copyright conditions exist for the posted code or they don't.
If a person wishes to insure that they can enforce their copyrights, its up to them to insure that the conditions are met.
I guess the only assumption I would make, with respect to Tek-Tip postings and copyrights is that in only a very very small majority does the subject even enter their mind.
I think you may be right in that publishing code in a tangible format establishes copyright to the original author. But that in itself brings ups some interesting and practical matters.
If I were to take some code that you posted and you decided to enforce that copyright - then what? Who would be the original owner - cian? In the eyes of the law, who is cian? And could you actually prove that you are cian, and the rightful owner of that code? and it was you, acting under that alias that posted the code? Who in the eyes of the law is CajunCenturion? How could you possible prove that I copied and used your code? Could you identify me? I think the law might have some difficulty in establishing who the real parties are. And then, you'd have show how you were damaged by the action.
As is the case with most legal interpretations, it will probably require that a case be taken to court, and appealed, so that a legal precedent can be set. Good Luck
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As a circle of light increases so does the circumference of darkness around it. - Albert Einstein