Seven years haven't been particularly kind to that (fairly slight, I think), objection. The specifics change but the principal points Marlinspike raises haven't. Of course, XMPP is more dead than ever, SMTP is still around and taking on the piece by moving the goalposts from protocols to something else hasn't become more effective.
It's declared dead by the people where every single one of your 20 nerd friends in your xmpp contact list has shut down their server, and that happened like 8 years ago in my case. We were on IRC before that and we're still on IRC, that's why IRC is alive.
