And there is one more important thing...
When you have a battle mode that runs online like Basic Brawl, the problem of what to do with hidden characters arises. If one of your opponents chooses a character you haven’t unlocked yet, it will be spoiled for you immediately.
But even without this mode, given the proliferation of the Internet these days, the existence of hidden characters is going to get exposed anyway.
So, this time I’m moving in the direction of not being too hung up on hidden characters.
This makes me think there are more unrevealed characters, maybe a lot more. If he's referring only to this hidden characters already on his site, then anyone reading this would already be spoiled.
EDIT: Can you play with your user created stages online? If so, how would that work? Maybe you can't, since a user could potentially arrange platforms to spell out the word "fuck" and we can't have that now can we.