The ethical standard that you are proposing — do not make public copies of things that other people have posted on the internet, even if they were published anonymously, even if you have explicit permission to do so, as in this case — is a serious danger to our intellectual culture. It would have prevented the creation of Google Cache and the Internet Archive.

In the age of the printing press, once a book or newspaper was printed and published, it was very rarely lost, despite the best efforts of book-burners — simply because there were many stable copies of it in existence, one for every two or three readers. I believe that this newfound resilience of knowledge has benefited humanity substantially. (Perhaps you disagree.)

In the age of the WWW, this is no longer the case. A web page can easily have hundreds of thousands, even millions of readers — more than all but the most popular of books — and still be lost to posterity through simple carelessness or lackadaisical attitudes about archival, because a single stable copy can be accessed by all of these readers concurrently. I have web pages from ten years ago (e.g. http://canonical.org/~kragen/x-pretty.html) and the links have nearly all rotted.

Consequently: if you find something on the web that has enduring value, by all means, make copies of it, and publish them so that other people can do the same. If nobody does, it will almost certainly be lost in a few short years.

Promulgating pseudo-moral injunctions against such copying could consign valuable information to the memory hole much more effectively than any Nazi book-burning parties ever could.