That isn't split screen multiplayer. That's separate screen multiplayer. I've seen it before. I don't really like it, especially as the only option.
You're right about the online co-op. I misread that. I don't really understand why there would be online multiplayer without a co-op campaign. That's the entire point of the game. I guess a versus mode might be fun (if that makes it in), but it sure would have been nice if the campaign had online co-op.