I agree with tye's analysis. It is fact (as he and Old Gray Bear both noted) that posting to a forum such as this DOES restrict one's ability to later cause that contribution -- no matter how wise or trollish -- to disappear
But, more important, I believe such posting SHOULD be tantamount to irrevocable waiver of any right to revoke what tye calls "license to distribute."
Hence, tye's "'legal notice'" deserves support and action... even if some could argue that it smacks of a "shrink-wrap license" scheme.
Tangent: I quibble -- nay, even quarrel-- with this one section of Old Gray Bear's presention:
On the one hand, I have to support X in his wish to remove his writings from general circulation. He wrote them. There was no 'license' attached to it releasing the words and ideas to the Public Domain. He is able to edit the node content at will. His retraction is merely a severe form of editing, but it is His Right.
I suspect we'd be well served with the view that the right to edit one's comments in a thread to which others have contributed should be restricted to strikethrough and insert. The would-be retracter can easily enough use available mechanisms (css such as:
Posted, knowing that some flaw in my current thinking may someday have me wishing I could not merely retract, but could actually delete this rambling. <G>