It doesn't have to be stated to be implied.  I have seen claims that bitcoin classic is an altcoin, and I have seem bitcoin classic threads moved to the altcoin section.  I've never supported bitcoin classic, but to the best of my knowledge, it is another client that follows the same protocols on the same blockchain until/unless there is a believed/detected "consensus".  I have also seen similar behavior surrounding another (even more questionable and less supported, but nonetheless allegedly compatible) client whose name I don't recall.  So there was no XT altcoin, and there is no classic altcoin, and there was no altcoin for that other unnamed client,but at least some members of core (and/or the community) with some level of authority are abusing that authority and suppressing alternative (albeit poorly conceived) wallets as altcoins solely because they offer potential future support for potential future changes.  These actions practically scream "it's my way or the highway" so the suggestion that no one has come out and said that means anything is a bit of a farce.