I have one: clearInput(), which clears the textarea, is tied directly to the addition of a new status, not to the submission of a new status via that textarea. Any other piece of the app that adds a new status (from other users, from automated systems, whatever) would clear what I'm typing. I can't imagine why you'd do that.
Haha, of course. I guess it was just a moments blackout — I was probably just too focused on making Backbone easily understandable. There might be some strangeness in there, but hopefully most readers have a better understanding of Backbone after reading it. And I don't have time to change it now either way.