From my personal experience which seems fairly in tune with his and yours, I would have to third Jeff's statement.
I'm sure that telling his family is dreadful in his eyes; I told my girlfriend long before I told my family, and I only told them because I was essentially forced to, (it was a "either you can tell them or I'll tell them" situation). Being forced into telling them was about the least comfortable thing I've ever had to do, and I still harbor plenty of resentment against the person who made me do it.
also, like Jeff said, an intervention probably won't magically zap his problems away. I told my family a year ago, and in terms of tangible healing, not a ton has happened since then.
I would say that if you want to be respectful of him, and yet gently proactive; you should support him, stand by him, accept that it will probably be a long process, and that he may well lie to you in the future, but lovingly nudge him towards anything that you think might help