To be fair, RSS isn't an either/or. Quite the oppoiste. You make an RSS feed and bring users into twitter to reach them. Ideally being able to move people to your own hosted service and they then interface with the base news in the same way, on their chosen RSS. Even if the link may take them to a blog instead of a centralized service.

Issue is that the bird app doesn't want this middleman between them. They want all the users' attention.