Could you talk to him about the drastically lower life expectancy, the extreme incidence of alcoholism and drug abuse, etc., that correlate with homosexual activity? When you don’t want to bring up a moral point - perhaps because the person is an atheist, as your friend is - a point about mortality might at least be taken as kind concern, rather than judgmentalism.
We went dry at the same time. November 17th, 2009. Him at 22:00, me at 20:03 (I had a drink to finish, and we are 2 hours apart). So that bit is a no, though a nice idea. So much of this is screaming “none of my business” its hard to even talk about it.