I would think that most people would be very surprised if Perlmonks didn't present their work to other users, which means they are expecting Perlmonks to distribute their published works, and have implicitly granted them the right to do so when they create their node.

The Author's copyright gives them the ability to grant Perlmonks permission to distribute their work, but without a written contract in place they are going to need to convince a court that their permission to Perlmonks can be revoked.

(i.e. I think it is obvious that an Author is implicitly granting publishing rights to Perlmonks, and without an explicit contract it is the Author’s burden if he wants to change that.)