I'm in agreement that I wouldn't necessarily choose XMPP for Twitter but under different reasons. There is literally nothing holding back the XMPP protocol from

I'm in agreement that I wouldn't necessarily choose XMPP for Twitter but under different reasons. There is literally nothing holding back the XMPP protocol from saving and publishing messages to the public viewing. XMPP is the eXtensible Messaging and Presence Protocol and suppose to be extremely modular so I really don't think what you're describing is impossible.