You're misinterpreting what Wikimedia's "free knowledge" mandate is about. They have a hard-line requirement that the knowlege they distribute is legally free, for example - it has to be under an open license. archive.today is quite the opposite of that. They don't just archive any old knowledge willy-nilly, they've got standards. And so forth.
Simply running an archive.today clone would not fit. The "source documents only" archive would already be stretching the edges rather far. There's already Wikisource, for example, and it's got the "open licenses only" restriction.