Earlier quoted context omitted.
In what world is Paper, Rooms, or Slingshot even remotely successful? And obviously the messaging service attached to an already massive social network would be compelling, that's not really an "experimental app" by any definition.
I don't think the commenter implied, or meant to imply they were successful.
Ah, my loose reading. I read it as "he must find something Twitter can be successful with, as Facebook... etc"
I see now that I was wrong there!