Gutted, sounds like you had a good conversation. I understand your friend's dilemma ("it's either the witnesses or no organized religion at all"). I had that same issue years ago, and that's what kept me in for longer than I should have...
But here's a way to approach that issue. Ask him to think about what "organization" he would have needed to join in the year 600 A.D; 1200 A.D., 1700 A.D., etc. The point is that the Witnesses admit and recognize that there was no real "organization" from the 2nd Century A.D. to the time of C.T. Russell in the late 1800s. So, who's to say that today is any different? In other words, isn't it possible (perhaps even likely) that today is no different from 1600, 1700, etc. in terms of there not being any "organization"?
See, as Witnesses, we are conditioned to view things through a particular lens--namely that we are living in the Last Days and there must be an organization doing the worldwide preaching work. For years, I used this "logic" to squelch my doubts about the WTS/JW faith. But, if the JWs are wrong about 1914 and the Last Days (and they are), then there's no need for there to be an organization doing the worldwide preaching work--even under WTS theology.