Standard disclaimer: I ain’t a lawyer, but a summary seems in order. The OP raised three points:
The question was about whether you can post material where you have been given permission by the copyright holder. The answer is: the burden of proof of whether you have permissions rests with you. We have neither the time nor resources to check each quote that goes beyond “fair use,” and our standard practice is to delete such material. Often we post in the thread that, if the poster thinks it was deleted unfairly, they can send us an email proving that they have some sort of copyright permission (or that copyright has run out) and we’ll restore it.
Also obviously, we are very forgiving if someone runs afoul of this rule now and then. Repeated abuse of the rule is a serious offense.
The objection was, what will the ISP do if someone is lookin’ for romance on our boards? I agree that there is a slight ambiguity that this applies only to the paragraph it is in. I believe it applies to the prior three or four paragraphs about various things that cannot be posted (illegal acts, copyright issues, selling, etc.) Agreed, it’s pretty much useless now but it wasn’t then… and, in some circumstances, a server might actually do something if the offense were egregious.
The first response here (as made by others) is that it would be a pain in the arse if a person, after being banned, demanded the removal of all their posts, cleansing of all posts that quoted them, etc. A mass delete isn’t enough: when a starter post is deleted, the whole thread is deleted, which would wreck the history. And, of course, if the 3rd, 4th, 7th, and 10th posts were deleted, it would kind of make hash of the flow of a discussion.
The second question on this seems to be whether “in any manner” might include without attribution. I think not: first, the actual quote is “to reuse your posting in any manner.” [bold mine] The prior sentence also refers to “your own work.” The Registration clearly recognizes authorship and would obviously attribute such.
Suppose Cecil or Ed wanted to quote a thread in a Straight Dope book (this is the only use the READER has made of board-posted material to date, so far as I am aware.) The concept of finding all the posters to get their specific permission, when some of them may have left the boards long ago, would be a nightmare. Hence, the language gives the READER the right to use such material without having to go through hideous legalisms.
The READER is a weekly newspaper, that has published the works of many, many authors over the last 30-some years, and has never been accused of failing to attribute such works. Our instructions as moderators are to be overly zealous in protecting copyright works; if there’s any doubt, we are to err on the side of caution and protection. The READER doesn’t want anyone misusing its material, and therefore does not allow posters to misues the material of others. I don’t think you need have any fears that “in any manner” implies illegal use or unattributed use.